That's because it's actually French.
Nah, seriously, that's why traveling the country is fun.
Each and every region has its own mood and traditions, often influenced by neighboring countries, which is something natural.
You can see it in the architecture. For instance, Nice and its surroundings have some kind of Italian vibe, for the same reason that Alsace looks a lot like traditional Germany or Switzerland.
These cities just sit on borders.
France is a nation that was gradually developed around a centralized state that started off from old monarchy. The French Republic itself remains a rather centralized system, that's supposed to maintain some kind of unity between all regions of the country, up to the overseas. It doesn't work as anything federal where local powers are stronger, even though the central government grew a bit more flexible over the past couple of decades.
The system is questionable in that it is mostly profitable to the Paris region where much of the wealth has been centralized. Often, some complain about that, like in Lyon for instance, that's a city with a lot of temper.
That being said, it's never been homogeneous. Somehow, each region has maintained some of their traditions, that actually keeps the whole thing diverse enough.