I have only spent about a year in the US, but to me the difference was stark from what I'm used to in Europe. As an example, I've never encountered a single shop cashier who didn't talk to me. Everyone had something to say, usually a variation of How's it going?. Contrasting this to my native Estonia, where I'd say at least 90% of my interactions with cashiers involves them not making a single sound. Not even in response to me saying hello, or to state the total sum. If they're depressed or in an otherwise non-euphoric mood, they make no attempt to fake it. I'm personally fine with it, because I don't go looking for social connections from cashiers. Also, when they do talk to me in a happy manner, I know it's genuine.
Does it translate into people wanting sycophantic chat bots? Maybe, but I don't know a single American that actually likes when llms act that way.
Politeness makes sense as an adaptation to low social trust. You have no way of knowing whether others will behave in mutually beneficial ways, so heavy standards of social interaction evolve to compensate and reduce risk. When it's taken to an excess, as it probably is in the U.S. (compared to most other developed countries) it just becomes grating for everyone involved. It's why public-facing workers invariably complain about the draining "emotional labor" they have to perform - a term that literally doesn't exist in most of the world!
Service industry in America is a different story that could use a lot of improvement.
Or is carrying a gun...
Let me guess, you consider yourself a progressive left democrat.
Do I have any source for that? No, but I noticed a pattern where progressive left democrats ask for a source to discredit something that is clearly a personal observation or opinion, and by its nature doesn't require any sources.
The only correct answer is: it's an opinion, accept it or refute it yourself, you don't need external validation to participate in an argument. Or maybe you need ;)
I don't, and your comment is a mockery of itself.