The perfect example is speed limits: everybody thinks they're good and yet they all seem to classify all other drivers into two categories: slowpokes and maniacs.

Nobody seems to be able to agree on what a responsible set of rules is around the speed of vehicles.

That's because they are slowpokes and maniacs: In a decently flowing road, the majority of distinct cars you see are either moving significantly faster or slower than you (and the more extreme the difference the more likely you are to see them). Of cars that go at a similar speed to you, they approach you / you approach them more slowly so you'll see fewer of them.

This is entirely made up? Most people are totally fine with speed limits being what they are and don't say anything about it.