I don't care WHAT lights my car on fire; I only care how likely it is that my car will light on fire.
Hang on a second. You make it sound like gasoline or batteries set your car on fire, and then your "car" is simply burning. You do realize the gasoline is 99% of what is burning, and not really the "car" itself, right? So there's more to it than the cause or frequency, but the nature of the fire itself. Gasoline is particularly bad because it is a liquid that typically flows all over and around the scene of an accident, then it is the evaporated vapor of the fuel that combusts openly in the air. Essentially, it will spread and consume the entire car and surrounding area because of its liquid nature. Lithium batteries burn in an entirely different manner. It seems likely to me that a Tesla battery fire would be much more contained and thus less dangerous than a gasoline fire.
Your logic is like saying that headaches and strokes are equivalent medical events involving the brain, and you'd rather have strokes since they occur less often. I don't think most people would share that kind of opinion.