That's... not true. The question is "how likely is there to be an electrical fire in the Tesla, given that it has crashed (or is crashing)" not "how likely is there to be an electrical fire".

It's easy enough for things not to catch flame when they're being used properly; the real test is how things behave when other things are going wrong.

That's not to say that this means all Tesla cars are fiery death-traps of doom. Just that the sample size really is the number of crashed cars.