I grew up on the south side and lived for years in Lakeview; we moved back from Ann Arbor to Oak Park, much later, the only time I've lived "in the suburbs", and Oak Park is more urban than Beverly or Jeff Park are. And then, of course, even after we moved to Oak Park, I still worked in the city every day.
No, this doesn't track my experience of Chicago at all.
It's a class thing more than a geography thing. Culturally working-class urban Americans are chatty in almost every American city, save the most recently-urbanized ones (like PHX -- and even there there Latinos are chatty even if whitey ain't...)
Reading a bunch of these posts, a similar thought occurred to me. When I lived for a short time in Manhattan, I found the friendliest / most chatty were always working class types that ran small businesses or worked in the trades. I wonder if it is nothing more than these people are much more exposed to "strangers" through their professions. As a result, they are much less afraid to open a conversation.