Comment by vanderZwan

That's because the reference point of most Europeans is not the actual lived experience of people in the US but the picture painted by the media.

When I visited the US the smiles seemed sincere‚ no doubt about it. The interactions also felt strangely shallow, which was of course to be expected and even sensible in the cultural context (why go into depth with someone you barely know and will never see again), but that is the real reason it felt jarring compared to what I was used to, and often made it confusing to make sense of whether the politeness was sincere or not.

This was in California, and I have to add that I was 17 at the time so "making sense of other people" wasn't a highly developed skill yet to begin with.