Under water, high voltage systems would likely short out instantly.
12V system might be fine (depends), at least for a while anyway until the battery is drained through leakage current.
Laminated side glass can't be easily broken by the little hammers or spring-loaded puncher.
It can only break the inner glass, not the vinyl middle layer, nor the outer glass.
I have one in every car I own .. (w/ seatbelt cutter integrated)
Unfortunately, laminated glass provides better sound insulation.
Most high-end vehicles now use laminated side window glass (similar to the windshield).
It also prevents flying glass debris (of tempered glass) toward passengers in an even of side impact.