> Strangers are outwardly friendly for no apparent reason

Why should one need a reason to be friendly? Would you rather people be curt and standoffish by default?

If everyone is your friend then no-one is. I wouldn't say curt and standoffish, but it's good to keep a certain amount of distance and formality with people you're not actually friends with so that you both know where you stand.

Unless friendliness is an expected social signal, and there's a separate signal, known to the local culture, but not to you, that says, "I'm being nice but we aren't actually friends".

Well I said outwardly friendly. As in like we grew up together in the same neighborhood kind of friendly.

Same happened when I had interviews for American companies. They were so excited about everything and overly enthusiastic I can't help but thing I'm being interviewed by psychos.

In the United States this is considered a "normal" amount of politeness. In some other cultures it is considered weird and fake. Some Americans go abroad and complain everyone was "rude" to them not realizing the cultural differences.

I bet they'd recognize you if you were perceived as someone potentially "useful" to them. I noticed the friendships here are often centered around very pragmatic sense of utility.

This really bothers me. I don't care if someone is "cheery" as long as they just do their job. People justify tipping service personnel (bar tenders, waitstaff) over them getting a fair salary because if they didn't tip "how would I get good service? There's no incentive without a tip." I believe some people believe "good service" means fakely cheery while to me it is "you brought me my food." If you aren't faking a smile and elevating your voice you are being "rude."