NYC is full of transplants from other places, so quite a few people know how to hang out and chat. If you're obviously not a New Yorker, they might realize that friendly out-of-town norms apply and engage with you.
But being considerate in New York usually looks like staying out of others' way. It might seem like unfriendliness to out-of-towners, but it's a (perhaps counter-intuitive) form of courtesy.
