>>2025141If by any amount of time you mean walking 100m in warm weather to your friends living in the next house without adults watching through the window it's probably legal anywhere, even for a 6 year old, yes.
But if a ten year old decides he wants to go to town and do so it really seems to be illegal, so OP is right. Why else would the cops arrest the mom?
Also if there is a legal distance to go alone, maybe even depending on the weather, the police should really tell their citizens so they know where they are allowed to walk to.