Well, a post without the usual accusations here, bravo!
As an old diver, I remember the times when practically only air and thus air deep was the norm for sport divers. There were also accidents because divers struggled with the demands in combination with impairments associated with air deep. Nowadays, divers usually dive much shallower with air, so we older divers think there shouldn't be many accidents anymore. Unfortunately, that's not the case, and there must be reasons for that.
Speleo, as an instructor, you might be able to tell me how you prepare the students to deal with the requirements of dense air, CO2, high pPO2, and narcosis due to CO2, O2, and N2.
Or are these issues considered to be only avoidable through technology?
So what do you do to train the human body and mind for this?