I'm not sure humans have the reaction time to avoid an object thrown from an overpass.

On the contrary, over the years I've read on many occasions how drivers and passengers have been seriously injured or killed by the morons who get a kick out of dropping objects from an overpass.

https://www.tennessean.com/story/news/local/wilson/mt-juliet...

One brick can attack one car.

One bricked GPS system can attack an entire country. Or planet.

True, but humans can see a bunch of kids loitering on top of a bridge, get suspicious and change lane or slow down as a precaution