O N B Your straight forward setting out of the problem and a possible route out of it, are a welcome breath of fresh air.
The statement about witnessing pax not putting on their life jacket in the time and manner prescribed speaks volumes and is the kind of empirical information entirely absent from the planning of these matters.
As we all know, the so called 'safety' regulations are made by politicians and they have the sole intention of @rse covering. Which means that there will be no revision of these rules until enough prangs have proved that they make no difference!
I, too, have never set any store by manufacturers being able to achieve tests on the ground within a highly structured environment. They are only of certification interest, not even academic interest.
Lastly, with your experience so tantalisingly sketched out, are you writing a book? If not, have you considered the opportunity to tell the truth - if only as a warning to be ignored?