They weren’t designed for prolonged immersion in salt water.

I'm guessing you don't live in a city that has hurricanes or tropical weather in general?

Cars are submerged in water all the time in certain parts of the world and if you live in one of those places then there's nothing you can do to avoid it. Every car I've ever owned has at some point been exposed to water depths deep enough that the tesla battery would've been fully submerged.

It's not uncommon for a tropical storm to rain billions of gallons of water over a small area in a short period of time. When that happens you just can't keep your car dry.

If it destroys the car, OK that's an insurance job. But if the car catches fire it has the potential to burn down buildings/etc which is really really bad especially if it happens during sever weather when a fire fighter will not be able to respond potentially until days later even if the nearest fire station is a few city blocks away.

I'm sure this is a solvable problem. Also - it's worth noting only two cars caught fire and I'd bet a lot more than two EVs were submerged a widespread flooding incident like this one. There must be more to it than just "if you expose an EV to salt water, it'll burn".