Youre intuition is right, France is extremely centralised, but you have only 2m living in Paris itself, on a population of 75m. It's one ultra rich city holding absolute power over the rest of the vast majority of the country. Even people who live in the "Île de France" (approx 12m people) aren't really much better in terms of everything. France is so imperialist that even internally they have a core/periphery dynamic