What percentage of crashes involve a fire? Not the potential for a fire, that's like asking how many police calls are "man with a gun" situations, but actual fires. Very few- they are a fluke.

How many crashes involve being thrown about or out of the cabin? I don't have an exact number, but a lot more than those that involve a catastrophic combustive failure of the gas tank. By a lot.

I'd rather be hanging upside down in my car for an hour than being tossed out the window. Particularly if the car is still rolling, and in my direction. "Failsafe" is a term of the art- if it's going to bust, it is going to bust in a manner that ensures the greatest safety to the user.