We have our rights and personal freedom to do risky things, but I think one of the issues is this: What is society's (read: taxpayer's), tolerance for ultimately having to pay for another person's carelessness/stupidity/bad luck...including diving accidents?
To illustrate my point....
In most Canadian provinces, we pay a small monthly fee for our health care. Assuming the majority of people within the system are healthy, we're not a drain on the health resources, relative to what we pay.
However, let me take the recent case of a buddy of ours who, after experiencing some considerable discomfort after a dive, had some of the best care money can buy. He got an emergency response within a few minutes of the 911 call, all the delicious O2 he could suck back, multiple, (relatively) well paid professionals attended the scene (EMS, fire/rescue) and to top it all off, a chopper was flown in to whisk him off the one of the best hospitals in the country where, arguably, the top Doc and hyperbaric chamber in the land where readied for his arrival. For this level of care, he (like most of us) pays about than $100/mo, or so. No additional bill will arrive in the mail. No other charges, whatsoever will be levied against him.
Is that to say his care was free? Hell no. I can't imagine what it cost the taxpayers (including me!) for that level of care. AFAIC, it's money well spent, especially when it's a friend.
My ultimate point is this; for all the scuba divers (careful or otherwise), all the out-of-bound skiers, lost hikers, snowmobilers caught in avalanches, etc. that require expensive, professional assistance when their sport/hobby gets them into trouble, at what point will society say, "enough! It's too expensive to allow these activities to continue without consequence".
Government may not directly limit our freedoms by enacting laws to prevent us from doing what we love to do, but they can sure as hell make it too expensive and perhaps beyond the financial reach of many by charging user fees, or licensing a sport/hobby or worse, setting a cost threshold or cap for care, then billing the victim/patient for charges above and beyond. Can you imagine the cost for the care my buddy received?
I wouldn't want to be sitting in a chamber for an 8 hour ride thinking, "jeez, what's this gonna cost me???" But I can see the day when things we take for granted today, are less frequently enjoyed or worse, no longer enjoyed because of the ultimate cost of doing them.
I hope that day never comes for divers.