We live in an age of child supervision, whether you like it or not. Long gone are the days when parents tell their kids to go outside at 10 AM and they don’t come back home until the sun goes down. Something about the crime-conscious culture of the 80s and 90s made it so parents don’t feel comfortable letting their kids outside of the house unsupervised, and so often, they just don’t leave the house. 

There are definitely ages and places when/where a kid can play without supervision. If they’re over 8, they can probably play in the neighborhood without mom or dad watching every move they make. But if they’re under eight and at a swimming pool, forget about it. That’s one of those activities that needs constant supervision. It’s a significant burden to expect a non-parental adult to watch them while they’re swimming to ensure their safety.