Worth noting that this is a western city- centric view of children. It's much different for people living in small communities or near parents and other family. Children spend way less time near parents when the neighborhood is familiar and safe enough, and instead spend most of their time playing with other kids. Parents today spend twice as much time with their kids than 2 generations ago, and it's probably not because they really really want to, but that there is no other option. I'm also not sure if kids spending so much of their childhood around adults instead of other kids is better.
https://www.economist.com/graphic-detail/2017/11/27/parents-...