Suburbs often have physical constraints with the way houses are laid out making this "stoop coffee" approach more difficult, if anything. Houses laid out in a way that you're more likely to drink your coffee on your back patio surrounded by a fence or hedges to avoid being seen. And even if you are sitting in front of your house, neighbors are more likely to be driving by instead of walking so not very likely to stop and chat.
In densely populated cities, you are often in close proximity with other humans you haven't met yet. But there can be social and cultural norms to keep walking and avoid eye contact because social interaction with all the countless people you pass is completely impractical.
In densely populated cities, you are often in close proximity with other humans you haven't met yet. But there can be social and cultural norms to keep walking and avoid eye contact because social interaction with all the countless people you pass is completely impractical.
https://www.youtube.com/watch?v=2AoNuz1gjQo
So both environments have their challenges for impromptu social interactions.