To add another datapoint: I'm not even that old (born in the mid-80s).
When I was 9 I walked a mile to school with my 6-year old sister, unsupervised (and stayed at home alone for an hour after school until my parents got home).
At 12 I commuted to school on a city bus for an hour (with a transfer downtown).
At 14.. jeez, I'm pretty sure at 14 my parents left me alone in the house for a long weekend.