I think other posters have identified the points I wish to make but from my own perspective as a professional in a purely recreational diving capacity (long post!):
Diving is, I think we all have to agree, a very safe pastime - and I don't use the word "sport" on purpose. Regardless of agency training, diver fatalities are rare and I think we have to thank the industry overall for this, and probably also the litigious (is that the right word?) nature of the societies to which many of us belong.
Accidents which can be demonstrated to have causal factors in equipment/training/instructors/divemasters, whatever, are inevitably bad for business, and therefore it is incumbent on all equipment manufacturers, dive centres and agencies to adhere to minimum safe levels of practice. Some shops will adhere exactly to the bare minimum, but in my experience, the majority go well above and beyond.
Diving is much more commonplace in 2011 that it was in 1990 - there are, quite literally, millions more people who have experienced diving, even if they didn't take it up full time. The industry as a whole has learned to cope with this because actually, diving in clear blue current-less tropical waters is really quite easy - just like any other "sport" - and as one other recent thread here analogised - I can ride a horse, I learned how to do it in a morning, as long as they give me a mild-mannered mare. I am not going to attempt to ride the wild Mustang. On the other hand, after several years of experience and training, I could ride a motorcycle around a circuit at a speed which meant I would not win, but neither come last in a race.
If somebody wants to learn to float about with the fish without killing either themselves or the coral, great - but it's when these people attempt to dive beyond their limits that the accidents start to occur. A freshly-baked recently certified beginner diver - agency irrelevant - should not be diving the Andrea Doria, or even the SS Thistlegorm, in my location - just like a freshly qualified motorcycle rider or car driver should not be trying to win Le Mans, and I'm going for the mild mannered mare, not the wild mustang.
You can train to deal with all sorts of accidents or eventualities, but even the most highly-trained experts in their high-risk sports die when they push the limits.
Another analogy to draw would be the difference between diving and driving when it comes to "gas management", another constant topic of debate amongst "training experts" on SB. A Formula 1 car racer will have the exact amount and weight of fuel calculated to the microgram in order to make it to the next pit-stop whilst maximising efficiency involving weight versus speed, whereas somebody who is driving the SUV to the shops needs to know that there is some gas in the tank, and when the needle points to the big, red, flashing, E for Empty - you need to stop at the gas station - and the level of conservatism built into the fuel gauge by car manufacturers means that they will read 0 for another 30 miles, because car manufacturers know that a small but annoying minority of people will manage to miss all the warning signs.
So by analogy an advanced trimix wreck diver needs to calculate percentages and pressures to get from one depth to the next over a two hour decompression dive and they must calculate these things accurately because if they get it wrong, the best that they can expect is an extended visit to the chamber, and the worst, death. The average tropical recreational diver needs to know that there is air in their tank, shallow up when it's half empty, then make a safety stop when it's still a quarter full. A small but annoying minority don't pay attention to their gauges and subsequently drown.
The standards have changed because the philosophy behind diving has changed. It's accessible, relatively inexpensive, and a really cool thing to do. When it comes to reliance on dive professionals - sure, this has also changed. When I work as a guide I have - technically - very little responsibility for the safety of the divers in my group - they are all certified divers etc. etc. and should be able to look after themselves and I am there in a purely logistical and supervisory capacity, pointing out cool things. In reality, I am responsible for the safety of every member of that group, both above and below water, for the whole day, because if something goes wrong, the first person they are going to sue is ME. Also I point out cool things.
With regards to buoyancy and trim, I think that many recreational divers (not SB members, of course) regard buoyancy as "a good idea", and trim as something that happens in the hair-dressers. I hear many divers discuss buoyancy techniques in the same way that many of my fellow amateur bikers would discuss body position and the merits of dragging their knees - something they could not yet achieve, and probably never would, but it was a valiant goal they were seeking. After 6 years of trying, they kiss the tarmac with the outer edge of their knee-sliders and bask in the glow of success - but actually most racers don't drag their knees all the time - unless they are using them to support themselves whilst cornering at 180mph and the bike is starting to fall over - just like divers will talk about how they could hover for whole minute without moving up and down, when the secret to hovering is not being motionless, it's the ability to ascend and descend on breath control alone without moving your body.
Even though it's amateur chat, there are so many more amateurs gaining more and more experience that people will learn from these discussions and try to improve their techniques next time. Some of the worst divers I've seen are those trained 30 years ago - some still with horse collars - awful buoyancy, over-weighted, terrible technique and air consumption, but have accumulated thousands of dives over 30 years of safe diving. Who am I to tell them that they don't have perfect trim!?
90% of recreational motorcycle riders can't drag their knee - I mean - did you ever even try this on a Harley? - but the majority of bike riders actually don't do stupid things beyond their limits either. Occasionally, some do, and suffer the consequences.
I think this is the over-riding disclaimer for recreational dive agencies: "You're trained to dive in gin clear water as long as it's not too deep", but if your local dive sites require extra techniques, you really need further training - and hey, buy a course! As I always say - it's a business, I am part of that business, I love it very much, and exactly zero divers have died under my supervision, even as a novice instructor - can you imagine that!?
The recreational dive industry has a half-century of experience now and whilst I do in fact disagree with some recent PADI standards changes, I am disappointed more because they remove some of the theoretical training, rather than performance-based training. It could be argued that this has an effect on safety, but I draw the example that gas theory (such as it was) has pretty much been completely removed from the PADI Nitrox course. I don't like this, but I don't think it affects overall safety when diving with nitrox, because all a recreational diver needs to know is where to put the gauge, how not to break it, how to read a chart or set a computer so it tells them what their MOD is, understand that even thought the limits are conservative, if they should break them, THEY WILL DIE!!!
Again, practically speaking, they don't, even though they lack the extra theoretical knowledge about gas mixtures.
Diver training has for sure been heavily simplified compared what it might have involved 20 or 30 years ago, but also diving itself has become much easier. It's easier to learn, it's easier to find, it doesn't require that you're an expert to do it.
As an sportsbiker, I think it is imperative for all motorcycle riders to learn correct body position, throttle and braking control, but most riders just need to know how to go and stop safely without falling off or hitting other road users. I would love to see all divers have perfect buoyancy control, but the truth is, they don't, and they never will, because that is the preserve of a talented group of people whose numbers diminish the farther up the ladder they rise - but in their aim to achieve higher goals, they will become more talented riders or divers, with an improvement or throttle or buoyancy control being part of the process.
For divers that seek more knowledge and more advanced training, courses and materials are available, even from PADI, and yes - you pay money for them, because it's a business, and yes, we are encouraged to sell the aforementioned further training but hmm - encouraging people to become more experienced and knowledgeable divers - which they have to pay for, rather like advanced motorcycle training - is a bad thing?
People disagree with the philosophies of varying training agencies - PADI takes the bulk of the bashing but read how much stick DIR training takes - for entirely different reasons - but that is my point - people disagree - that's fine, but the world has changed and actually diving is very safe, even if the vast majority of divers are not, metaphorically speaking, capable of dragging their knee.
I think one could sum up the safety aspect of the dive industry something like this: "Accidents are bad for business". People are not going to purchase a product that is unsafe. If recreational dive training was so poor, I would be pulling bodies out of the water on a daily basis, and people would not want to go diving.
Suzuki builds great sports bikes, but they can't control how every rider will ride their bikes. Most, hopefully, will understand their limitations and not push the envelope. Just like diving - most divers can dive safely, if not well. A few have accidents because they are unlucky, or there is culpability from some other party. A few will try things beyond their training and experience and leave tragedy in their wake. And yes, as one other poster identified - there's a lot of Muppets out there... it is a talent show known as "the Human Race".
Safe diving all,
C.