Yeah, European countries have histories going back a thousand years or more. While there’s going to be some shared history in border regions (often they swapped back and forth between countries depending on who was strong and who was weak), there’s a lot of differences between them that are pretty deep seated.

If those countries shared a common language the cultures would tend to blend over time. When they speak different languages that process is a lot slower.

IMO the differences between major US cities are smaller than the differences between any given city and the rural areas surrounding that city.