So, after a student does a course with you, they are no longer capable of making an assembly error (which in a rebreather will lead to loss of consciousness and drowning)?
Would you feel more comfortable, despite your teaching skills and your student learning abilities, if, ultimately, the student at a later date would not be able to make an assembly error because the diving equipment (i.e. rebreather) rather than being designed as a Lego, it is designed such that:
It shall not be possible to assemble or combine the components or parts in such a way that it can affect the safe operation and safe use of the apparatus, e.g. by incorrect connection of the hoses to the breathing circuit.
???
Every diver makes mistakes (that should be the safest assumption... invincibility is for teens).
Jim didn't say people don't make mistakes. He said he does additional familiarization training for his students.
You just see what you want.
Rebreathers can never be 100% safe- nor can open circuit.
In your world open circuit regulators should be capable of detecting oxygen content and shut off when the MOD us reached.
Just silly.