> but seeing as literally all new cars have to have that system and we're not seeing people randomly braking in the middle of the motorway for no reason I can only guess it's fine.

But we definitely do.

https://www.cbsnews.com/news/automatic-emergency-braking-in-...

The price we pay for having relatively few false positives is a high false negative rate. For example, a Tesla won't stop for an overturned truck or the pedestrian standing next to it.