The place I mentioned where we lived for a month last summer was a relatively recently developed suburb, about 5 miles from the city center. Granted, it was hot when we stayed there, as it was mid-August, but we never saw anyone, besides ourselves, walking around that neighborhood, and the only people we saw outside their houses were about to get into their air conditioned cars, or else, operating lawnmowers or some other type of landscaping equipment. The fact that that neighborhood was designed and built without any sidewalks seemed like a pretty clear sign that walking wasn't really imagined as a way people living there would get around. The nearest stores were a couple of miles away and would've required crossing some pretty major (8 lane) roads to get to, anyway. After spending a month living there, we were grateful to be able to move on to a more urban neighborhood.
Where we live, now, in the city is very different. There are sidewalks everywhere, so there are people walking around the neighborhood everyday. Just looked at my Ring doorbell log, and ~25 groups of people passed by the front of my house in the past 24 hours, around 3/4 of them walking dogs. Neighbors who have dogs seem relatively more approachable. While riding my bike, I'll often stop when I see a neighbor I recognize walking their dog(s) and talk with them for a few minutes. After living in the country for 20+ years, where we let all of our pets roam freely, it's hard to imagine wanting to have a dog in the city. It seems kind of cruel for the animals and a nuisance for the humans to have to walk them around multiple times every day and to have to, literally, pick up their shit for them. It's hard for me to imagine anyone voluntarily doing that everyday. The upside of having a dog in the city, though, seems to be an opportunity for a bit more social interaction with neighbors, and it also forces people who might otherwise be completely sedentary to get out of the house and get some exercise. For now, anyway, I'll just stick to my bike for exercise. Days when it's raining or I don't feel like going out, I can just leave my bike parked in my living room.
There's an interesting dichotomy on our city block. One end of the block is mostly rentals, 3 units to a house, and the other end of the block is mostly owner-occupied SFHs. We and our immediate neighbors all own our homes, so have all 3 floors + basement to ourselves. Whereas, people at the other end of the block are mostly renters, who are just inhabiting either a first, second, or third floor apartment in the same type of 120 year old city row house. The mostly poorer, mostly browner people living in rentals at one end of our block tend to not have central AC in their apartments. Maybe because of a lack of AC, or maybe because of cultural differences, many of those renters can often be seen sitting outside on their porches or stoops, as their kids play on the sidewalk and street in front of their houses. When I ride by on my bicycle, I always wave and say hello to those neighbors who are sitting outside on summer evenings. The whiter, richer, homeowners on our end of the block all have central AC and, therefore, rarely come outside of their houses, especially during these hot summer days, except when they are about to hop into their air conditioned cars to head off somewhere.