In US cities it seems the norm is to never say a word to strangers about anything, ever, so it then follows that anyone who does talk to you is more likely trying to grift you. Which makes you even less likely to talk to strangers in the future, in a vicious cycle. I've never actually read Jane Jacobs but I'm pretty sure this isn't what she was interested in preserving. I don't know if it's technology, population churn, or what.