last names: part II

I have a Canadian friend who lives in France and she mentioned that it's best to just roll with the last name thing. Officially you keep your maiden name but sometimes they assume you have taken your husband's name. A little look on Wikipedia brought up this information:

"Since the 1789 Revolution, the law stipulates that "no one may use another name than that given on their birth certificate"; furthermore, the 1946 revision to the Constitution guarantees that "women and men have equal rights", including in the use of their birth name. Upon getting married, a woman keeps her maiden name (nom de jeune fille). She may, under her maiden name, for example, open a bank account, sign checks, obtain a passport, etc. However, marriage grants a married person the right to assume his or her spouse's last name. It is still a common practice for a woman to use her husband's name in this way, despite the fact that no official due process formalizes this usage. The majority of married women use their husband's name for all documents, official or not."

I personally think this is a confusing way to go about doing things and I'm not sure I agree with it. How do I prove who I am? I'm going to take the advice I was given and roll with it for a while (for now, anyway!).