This seems to be a modern, Western approach to thing. I've seen South American tribal folk give a 5 year old a machete to do actual work. I didn't see a lot of dismembered children.

A lot of it comes down to family training. The older kids teach the younger kids what to do and not do. This doesn't protect from every little thing, but life is not that safe.

You do need training however. I was in Montana as a child with my dad on business. The client lived way out in the middle of nowhere. He was a big man (bigger than my father who's 6' 1"). He reached into a drawer, pulled out two bear size handfuls of .22lr, showed me how to load the riffle (fortunately I'd been trained by my dad and grandfather on hunting small game around the farm) and told me the adults need to talk. What he didn't tell me is that it was a modified .22lr: full auto. I was in for a surprise when 10 rounds cracked out at supersonic speed. I was fine and had fun. It could have been bad though.