Yes the training used to be more until they split up the course, for those of you who don’t know the old PADI/YMCA/LA "Certified Diver" course would be equal to a Master Diver today.
I’m not sure I buy the training side of the story but the writer probably isn’t a diver and I applaud him for not calling them oxygen tanks. Most diving deaths are medical emergencies that just happen to happen underwater and most likely the diver knew he had a problem and kept diving anyhow.
The other is we get complacent, I knew a diveboat Captain of a well known east coast diveboat with thousands of dives who was diving solo, got tangled and drown on a Jersey wreck.
I’ve talked here before about a dive travel agent also with thousands of dives who streamlined his kit to the point he had no signaling devices and drifted in the Galapagos for 1:44 before we found him.
None of these has anything to do with what quarry, lake or ocean you are diving and everything about we are exploring a hostile environment and it will kill you if you don’t pay attention. I’ve had a couple of cars that tried to kill me and I slipped off a cliff I was free climbing. Life is like that, if you don’t pay attention it will bite you :(