Looks like another case of nature versus nurture, to me.
“Personal space” is largely cultural, and therefore learned, in my experience.
When I first moved to the outer ‘burbs down here, I’d get annoyed in the local stores, because I honestly could not distinguish, between people standing around shooting the breeze, and people who were standing in line for the cash register.
It’s still hard to tell, but I’ve learned if they’re facing the register, they’re probably in line, even though they’re spread out with three feet or more between them. They’ll line up to the back of the store, to maintain this spacing. It’s really sort of odd, but I’ve gotten accustomed.
My grandson went to NYC in March, I asked him what the most memorable thing was and he said that it was walking shoulder to shoulder with people you don’t even know.