Parents today are overprotective (this includes me!) and don't realize that it actually damages their kids. I was 5-years-old when my parents would just drop me off to the kindergarten and then I was on my own pretty much the whole day after kindergarten finishes in the afternoon. I would go to different classes kilometers away, crossing roads, etc. and it was common practice. I don't think kids get injured less today than when I was a kid. Also, my parents would send me to the store to buy them beer or cigarettes - all you needed back then to either bring a handwritten note from your parent or for the salesperson to know you and know your parents - I don't drink, I don't smoke. We always underestimate the power of the forbidden fruit! Leaving kids on their own makes them more responsible and independent.
I highly recommend Free-Range Kids [0]!
[0]: https://www.freerangekids.com/