Actually my parents would have sent me off to ski on my own at 8 or so and by 10 they'd have sent me to Canada on my own to ski, if it wasn't for the fact that my dad was tighter than a duck's arse under water and wouldn't have paid for me to get the bus to school, when I was 4 years old, on my own, if it wasn't for my mum who would have divorced him for trying to make me walk (and despite how this sounds like exaggeration for comic effect, I swear to you I did catch the bus 5 days a week on my own aged 4 and my dad did begrudge the two pence it cost)! That wasn't so uncommon in '72. Certainly by 5 years old all boys were expected to leave the house without supervision for 3-4 hours at a time at the weekends and by 7-8 years old most of the day.
Our parents would periodically find out what we actually did during that time, when somebody would end up in hospital. Everybody would get a good hiding, we would be forbidden from doing whatever had caused the injury, with very little expectation that we would obey, and it would be chalked up to a good lesson to look after yourself better.
I'm not sure that what was, by today's standards, neglect was entirely good for us, but I also wonder if we are increasingly breeding generations of people without the necessary degree of self confidence and initiative needed to decide to do something completely new and take care of all aspects of it, including safety, themselves. I mean without some supervision or guarantee that everything will be safe. Except of course, those whom are sent to posh boarding schools, or those whom are genuinely neglected.