Well, I was watching my sibs from about 12 years old on..but the world was a bit different then.
I'm the oldest of four so had to be responsible for them. And as I drove quite early on family trips (imagine letting your daughter drive in three years, or mine right now!) from fifteen and a half on, with seven people in the car and a very large van, they let me drive all the kids around once I had my license at sixteen. I mean, they assumed I'd be responsible.
In Indiana, we came home and the answering machine had a message from another mother as the school had let the kids out early and our child couldn't find us and went to her house. We felt terribly guilty, then discovered she hadn't given us the note notifying us of the early dismissal. A big discussion ensued, and I had a key made for her as I'd much rather she be able to enter the house, we had senior neighbors who could look out for her in case of these things, and so in that context I was comfortable with it.
Depends on the child though.
My oldest takes after me though...and at five, managed to fix me meals after her brother was born, answer the phone, and let me sleep.
Our kids stay home alone for about two hours at a time.
I think that if a child has never been able to react in an emergency, they will flip out when it happens.
This however, looks as though the parents were trying to teach their child a lesson of responsiblity that he wasn't ready for.
That's the key really, responsiblity comes in small doses.
Here's another thing we did, we decided to teach our daughter the rudiments of backing up the van etc...at about 12 as few people are used to an automatic transmission.
I was shocked when I saw her doing it with her dad, then thought how silly, my dad taught me at that age too. Learned how to shift gears very early that way.
We thought that in case of an accident or something, she could back the car.
One similar lesson of consequences of actions, if for some reason the child doesn't give me something to be signed, they don't go to the event. They know that I have better things to do than muck about with these things.
_________________________
I was born under a wandering star.