As an outsider sometimes you are not aware of cultural norms, but I always felt the margin for error for what Americans considered "acceptable" was too narrow. There was no benefit of doubt, and sometimes an explicit dislike for someone who did not immediately fit in.
The truth is that countries, or even cities, are not monolithic entities. It's entirely possible for each place to have two characters. In the same NYC that was largely kind to me, I was also stalked at by some lowlife with presumably evil intentions.
In NYC, there's always too much going on. The critical thing people lack is time. So they interact in ways that don't waste time. That may be being polite... in context.
(source: lived in NYC for 15 years)