Gasoline fires don't spontaneously restart, either.

I've also never given much thought to parking my gasoline fueled vehicles inside my garage. When ICE cars do spontaneously ignite, it's never because of the gasoline.

I do sometimes think about how prudent it is to park my Tesla underneath my kids' bedrooms every night while it starts charging unattended after everyone is asleep. I'm glad to have a smoke alarm in the garage.

I am glad you have a smoke alarm in the garage I am now thinking how mine died in the garage and I sleep right above it. If it was me in your position I would make sure I used a linked fire alarm system where if one goes off they all go off. It will buy you precious extra seconds getting your kids out as fires can spread incredibly fast.

Yep, ours are all wired together. Sometimes when I am a little over-enthusiastic searing a steak, I think they can probably hear the ruckus a quarter mile away when every single alarm goes off at once. Makes me feel somewhat secure that I'll be woken up if there is ever an actual fire.

ICE engine fires mostly happen on old, unmaintained cars. Very few almost new $60k++ ICE cars spontaneously combust because of the fuel (a short circuit in the dashboard would cause a fire in any type of car). When they do they're relatively easy to put out. And it's a bit easier to spot a potential fire hazard in advance, providing you do the regular checks.

On the other hand a battery fire is about the worst kind of fire a regular person might encounter in day to day life. It's a nightmare even for firefighters. They are very hard to put out and don't want to stay out. There's also no easy way to inspect the battery for such fire-causing potential defects. A single defective cell can cause a thermal runaway event.

It's the unpredictability that makes battery fires more dangerous. At this point we have no feasible preventive measures, no yearly service visits, no visual check for leaks, nothing.