This is interesting to me because growing up poor and with a single parent, I was allowed to run wild at a very young age. There was a whole crew of young kids

This is interesting to me because growing up poor and with a single parent, I was allowed to run wild at a very young age. There was a whole crew of young kids in our apartment complex that would hang out and wander around unsupervised during daylight hours. Our parents were busy working and they probably needed some occasional time alone in those tiny apartments (my mother and I shared a 1 bedroom). As for "high income cities" it doesn't get much higher income than Manhattan and I would be shocked if I saw some under-10 kids wandering around here on their lonesome!