My parents did it with me when I was ten so, depending on the kid, it could be believable or at least not a huge stretch for latchkey kids. We had specific rules I had to follow if I was there by myself. We had neighbors close by that kept an eye on us if an emergency occurred though so I don't think it is necessarily much of a stretch and he did have an older brother that was supposed to be watching him as I recall. That's probably what's wrong with me I still enjoy the first half of the movie and it captures the feel of a family and feels amazingly authentic. The problem I have always had with the film is the shift into complete fantasy. I don't think it's successful but I'm in a I or'it you that feels that way. Still, if you look at the growth and confidence of Spielberg as a film director, it's an amazing example of his depth of talent.