I think the 'rudeness' part comes from mutual misunderstanding of how the cultures of France (Europe in general, but Europe is too varied culturally to discuss all at once) and NA are actually very different on many aspects.
When I came to Canada I found Canadians unbelievably rude, which is not something I expected at all! It's just that rudeness is not the same for everyone, as politeness is not the same for everyone. As a French person, I found rude that people refused to tell me what they think of me, and found that rude and cowardly. Not polite at all. But then I understood.
I found that the big difference is that in NA, you show interest or affection by complimenting people, or generally, by making it look like everything is okay, great and must go on like that. In France, you show interest/affection by helping people get better (which means criticizing, sometimes in a tough way).
One example that came the day I arrived in Canada: I came for a PhD degree, and the university had accepted me knowing that I was the top student for the practical part of my previous degree, at a good uni in France. Then they saw my grades.. I had the lowest passing grades for an undergrad degree! 20% too little to even think of a PhD. So I had to explain that 70% was pretty much the highest I could get in France, as I was just a student, and that on the French grading system, no one could have 100% because it's impossible to be 100% certain in science, and that the 90% they were requiring was making it look like I was supposed to be the world top specialist in the field. Good I knew about grading differences, because it would have been stressing.
Anyway, yep, for most of my studies, I was not rewarded for knowing, but reminded that I knew close to nothing. A very different mindset.