It's not just quality of ingredients (though that is part of it); it's also culture. Southern Europeans (understood in a broad sense to include the French) are

It's not just quality of ingredients (though that is part of it); it's also culture. Southern Europeans (understood in a broad sense to include the French) are less likely to tolerate regularly eating highly processed food, takeout, fast food, etc. and much more likely to cook at home from scratch than Americans are. Of course, the distributions overlap; there are Americans who eat like the stereotypical French person, and vice versa.