The rules are not "for" something in France. They just appear out of committees and political compromises and are often half-assed implementations of nonsensical middle-ground between two coherent positions. Some may occasionally align with public interest.

One of the things you learn living in France is a sense of the rules that make no sense and that everybody is probably disregarding, and the ones that are actually useful and probably enforced.

Always smile to a clerk. They will tell you which mandatory paper is not mandatory and which rule you can break. They will also tell you which rule the state is incapable of following and how to get around it.