It would also depend on bilateral agreements. For example, a friend of mine is from South Korea. Although she's been in France for over 5 years, fluent in French as any native, educated and pretty well established (she lives that wealthy neighborhood of the 16th arrondissement of her dreams
), she claims it's easier for people from the former colonies of the French to renew their visas, complaining about it. I couldn't say how accurate what she says is, though, as she's a pretty tough person, a little harsh to others sometimes.