In your region, what age is fine for a child to go on the bus alone?
We currently live in Estonia, and in rural areas (near Nõo in particular) we notice children of perhaps 6 years old, or even younger, getting on inter-town/suburban busses by themselves, taking their seats and getting off on their stop. Probably, their parents / grandparents take them to the bus stop and meet them when they arrive, but it is still impressive.
How is it in your country / region?