> In the US, it’s always considered the fault of the person who read ends someone.

This is simply false. Brake checking is explicitly a traffic offense in some states, and can get you cited under something like reckless driving in some other states. Your insurance company is not obligated to find the other driver at fault if you're cited for brake checking.

Yes I’m sure that driverless cars are purposefully trying to cause rear end accidents by brake checking.

Your reply is totally relevant in the context of someone blaming driverless cars for stopping when it doesn’t know what to do.

[delayed]

I've been brake checked by a cruise car in SF. I had a dash cam and had I hit it I'm confident I would have been cleared and the robo car that stopped suddenly randomly in the middle of traffic would have been at fault.

They literally have signs on them that say "warning, stops suddenly" , not a joke, literally

Don't brake check someone and rely on this as you will end up partially at fault for creating a dangerous situation.

But braking for safety is always allowed and the person behind you is supposed to leave room to allow that.

Not always - if you have dashcam footage that proves brake checking or other poor behavior, it can be decided in the rear car’s favor.

This is not true at all

So if you are waiting at a stop sign, red light, and someone crashes onto you from behind is it your fault by law? Hard to believe

They said the person that rear ends someone is at fault, which in your scenario is the person who is who crashes into the waiting person from behind.

No, the opposite. That's you getting rear-ended, not you rear-ending someone.