Even since I was 10 or so I would often come back to school on my own. Then let myself into our apartment. Eat some lunch, do homework, play until my parents came home in the evening. I was effectively often alone for about 4 or so hours.

I wouldn't let my kid do it here in US. Not because I wouldn't trust them or think it is dangerous. But because I am afraid what neighbors, school, CPS would do.

My co-worker let his kids play in the cul-de-sac for an hour while they watched from the house. An anonymous neighbor reported them to police, and a sequence of embarrassing calls at work ensued, statements to police, follow up visits from police, etc.

And this is not some dangerous part of the city. This is suburbs, as safe as they come.

But apparently you are never safe from neighbors with an agenda.

And the thing is, there is nothing you can say or do, even if you knew this neighbor. "Well I was worried for the children!". Unless they openly confessed it was because you cut the lawn wrong or they don't like the color of your house, there is nothing you can do to them (well maybe turn evil and report them for other irrational fears -- terrorism "but I was worried about this country's safety, swear heard them talk about buying a lot of fertilizer").

The interesting thing is, once those in power act irrationally about something. There will always be people to exploit that element. I heard from my grandparents how neighbors would rat on each other imaginary things during Stalin's times. The results were usually the neighbors family would be taken in the middle the night and sent to Siberia never to be seen again. This is of course, an extreme example but it illustrates, how irrationality can and will be exploited.