Crab,
How far in advance would you have the customer book the flight....and the necessary training to use all that gear?
Surely you don”t think it fine to hand a passenger a PFD and Puff Bottle...as they head out the door to the aircraft do you?
SAS, every passenger we took over the water on SAR was given a goon suit. life jacket and a through safety briefing - it took well under an hour.
Any that we took over water at night, had to have been dunker trained.
You wouldn't bungee jump without a briefing and a safety cord.
Silver Pegasus - you defeat your own argument about immersion suits - yes they are slightly more restrictive (modern ones are much better though) but they keep you alive long enough to orientate yourself and make the exit without the debilitating effects of the cold water stopping you.