The error rate would certainly go up at first due to the additional complexity, but the cost of each error goes down. Besides, I have to switch the speed at which I'm driving far more granularly than at county lines, and no one's worried about a car's ability to handle that.

I don't disagree that sometimes central decision making is good, but in a complicated situation where any decision will have some negative consequences depending on the specific context seems like a textbook case of not being one of them.