I've never in my life have been in a city where it would be OK to just say "hi" to a person you don't know and are not planning to get to know. This sounds... l

I've never in my life have been in a city where it would be OK to just say "hi" to a person you don't know and are not planning to get to know. This sounds... like something out of pure fantasy. Where on Earth do people do that?