> In NYC, people are nearly all strangers and in a big hurry
Maybe you've only been in midtown Manhattan? I live in a Brooklyn neighborhood where we bump into people we know constantly and no-one is rushing around madly.
Every time in NYC, I've spent nearly my entire time in Manhattan, excluding one trip to my friend's folks' place on Staten Island. That seemed much better in terms of the odds serendipitous bumping into friends, but still less so than mountain state.
Anecdata: currently living in NYC in a very similar situation to GP (possibly the same neighborhood based on their description?), and I have easily 10x more such serendipitous encounters than in any of the 4 other places I've lived (from suburbia to another major US urban center).
It's a pretty well known phenomenon here that you see people you know (or, say, notice the same person twice in the same day in totally different parts of the city) way more often than you'd expect. Sure, 10x as many people live here, but you see 100x as many people each day.
The "people who don't live here assume that residents are rushing around places that look like Midtown 24/7" is another pretty well known phenomenon, fwiw
Maybe you've only been in midtown Manhattan? I live in a Brooklyn neighborhood where we bump into people we know constantly and no-one is rushing around madly.