You can get a license to dive for $300 in 3 days or for $1000 in 4 weeks. Not hard to figure out which shop will sell the most high margin equipment. The vast majority of people want what they see as the "license". A buddy I dive with had the 3 days and got the cert. If it would have taken 5 days he wouldn't have done it. He has been learning ever since. I took the course over several weeks. I've been learning ever since too.
All of you are focused on one side of equation-instructors, except
@BRT . But every equation have two sides, second being students. There are some people getting into diving for bragging purposes, card collection etc. and there are people that love diving and strive to be the best they can be at anything they do. Therefore we have people enrolling in PADI or NAUI,BSAC,CMAS,GUE. Point is, you can raise standards, but if people are not interested they will walk away to find lesser restriction course for what they want.
Why is it that GUE or BSAC produce "better" divers? Instructors? Probably, but definitely not the only reason. People that come to these agencies have a certain mindset, and they are actively working at getting better,well, most of them.
When I researched my options,PADI was easiest. Finish OW, do 5 more training dives and you're AOW. Cool, but I am not in this for being cool. I also love to be alive ( not that I am saying every PADI AOW will die while diving).
Second option for me was CMAS. 20 dives to get AOW. Still not great, but better.
And then there comes student/diver mindset. I finished my OW, with some holes in my training, but I knew that and worked every dive to correct my technique ( by asking more experienced divers about my trim, buoyancy, breathing , watching tons of videos on YT and spending hours and hours here on SB sifting through information). A friend of mine, with even bigger holes, simply do not care. He got his card and see no room for improvement. Even worse, a girl in my class, which was way better than me, now dives like she never saw scuba gear. She does not care,squared!
Instructors are not perfect, but neither are students, so it is unfair to put all the blame on one side only.