I don't disagree that urban planning is a factor, but I think there's more to this. A very common theme when talking to people in the US is "this neighborhood

I don't disagree that urban planning is a factor, but I think there's more to this. A very common theme when talking to people in the US is "this neighborhood used to have so many more kids out and about!" Even in the neighborhood I grew up in, where my parents still live, there are far fewer kids around, even though the neighborhood's design and car traffic haven't changed at all. Where are they? Are their parents driving them from place to place? Are they staying inside staring at screens? Or are there simply fewer kids due to falling birthrates?