My guess is that declining fertility is the dominant cause of kids not being able to play without parents. They don’t have as many brothers and sisters! And of course this is a macro trend happening all over the world with enormous forces driving it. It ain’t gonna reverse barring a total collapse of modern women’s rights. We are clearly going to need new infrastructure for kids to have that alone free time with other kids in the absence of having 2+ siblings like Ms. Martinko’s kids. (Also the…