OK, so now write a law that makes a distinction here. What do you end up with? EU law.

The EU does not write traffic legislation, it leaves that up to the individual states.

Unlike the US, the EU is a collection of fully sovereign countries.

This was a mental shortcut, to exemplify EU vs US attitude in this case. I am from and live in one of EU countries, I am very well aware of that.

“fully” is optimistic - being a member of the EU means giving up some sovereignty.