We know there are differences within countries, but those differences tend to get exaggerated since you live in them. Even in European countries people tend to say "People from city X are very brash, people from city Y are very warm and welcoming", so they know that even though they consume the same news, speak the same language etc things can be different. Or they say "People from area X are very racist, area Y is very liberal".

But we also know that there are much bigger differences if you cross many national borders and language barriers by going to the other side of Europe, they too will have those micro differences but when going there you also get many major macro differences.