I live in San Francisco.
I didn't know YC published HN's demographics. Do you have a link?
Unless the wealthier, more connected, more educated readership of Hacker News strongly bucks every trend suggested by their demographics, it's pretty safe to say we mostly live in urban areas.
[1]https://www.citylab.com/equity/2012/03/us-urban-population-w... [2]https://www.census.gov/newsroom/press-releases/2015/cb15-33....
The preferred option is to do a little reading of your own beforehand, and to share whatever it is you know that makes you think the obvious answer might not be right.
You still have people in checkout lines on their phones or parents giving their kids a phone with YouTube or a mobile game to distract them. The older folk, as you might expect, tend to strike up conversation and bump into those they don't know.
I worked retail a few years in this town (which is finally coming to an end) and the few times I can remember strangers striking up a conversation with me were mainly them spreading misinformation.
A few years back, one elderly man swore black and blue that "they" were canning all of the "irradiated fish" from the Fukushima fallout and selling it to unsuspecting customers. Another lady told me the story of a man who just happened to be stumbling around "a major Chinese city" and peering into a factory window only to see that "the Chinese" were turning cardboard into cookies and selling them to us unsuspecting Westerners.
By no means are the above stories an indicator of country folk but let's just say I have my reasons for not jumping at the chance to talk with strangers. Half the time it's just an excuse for them to offload their stories onto me rather than actually being a two way conversation anyway.
EDIT: I just mentioned the overall feel of the discussions to my dad as he's the sort to strike up conversation with anyone. Having presented both sides of the discussion, he instantly discarded one side as "wrong" without actually weighing up any of the points. While it's anecdotal, it's no wonder I'm somewhat the opposite. Each conversation turns into a debate to win rather than a discussion.
Given "equal and opposite reaction[s]", I wonder if tribalism is inevitable? Did we ever actually defuse this kind of stuff in society or was it just hidden away due to geography eg; distance between rural and urban areas?
Even if this slight increase in social interaction did anything ("cash or credit?" -- "Credit, ma'am"), that's as ridiculous as fixing race conditions with sleep() calls (hehe, race conditions).
But to answer your comment: the comment was not about the chit-chat with the cashier, but other people in the line.