No it is not. Look, it's not as if "being submerged in water" is a common condition for these cars. They are commuter cars, not off-road vehicles. I'm sure the manufacturer's engineering team could come up with an automatic sealing mechanism, but that would come with trade-offs from both price and complexity perspective. At the end of the day it just is not worth it.

Dropping a car in the ocean is far, far outside of the design envelope. It is simply not reasonable to expect the manufacturer to add cost to endure that unlikely of an event.