[Turing_Machine]

There are some real problems with centralized systems. The obvious one is that if the centralized system goes down, things would become very, very bad in a very short time (thousands of cars effectively driverless, all at once...yikes).

Making each car responsible for its own collision avoidance is a lot more robust. If the sensors fail in one car, the others can take corrective action. For maximum safety, you'd also want the cars to be running different (but equally good) software, so you don't run into the type of situation where (e.g.) they all go nuts because the programmer didn't account for leap years or whatever.