That stopped happening in the 90s, where you would get reported to child protective services for letting your under 12yo children play outside by themselves unsupervised if it was outside of your property.

Other parents hear it and it creates a huge chilling effect. As a result, there are no other kids outside to play with, so for the few parents willing to buck the trend, it doesn't matter anyway and helicopter soccer mom has to play chauefer and sign them up for a million structured activities and play dates so the kids don't go nuts inside their houses with not being allowed to do anything.