It's a tough call. My ten year old would stay alone if I was running to the grocery store, a quick trip but that is it. He was not comfortable. Now that he is eleven he is much more comfortable staying on his own for several hours if I have to be out on an appointment. However, even now I don't let him walk anywhere in the neighborhood alone.
The tricky thing about walking home from anywhere is that there are unsavory characters, not just predators, but drug dealers, looking for a kid alone. My father (who was with the National Security Agency ) always warned me when I was a young woman, to never drive the same way home each day. He said you never know who is watching and when you never deviate from a pattern it is very easy for someone with bad intentions to be able to "get to you".
Is there a next door neighbor you can rely on to walk him home? Or at least watch out from their front yard? Once he is home, if he is a reliable kid, I think he is a lot safer.
Have you been through all the possible scenarios with him?
What if someone knocks on the door and says " Let me in , your mom has been in an accident?"
What happens if there is a fire?
What happens if he gets sick?
What happens if someone approaches him on the way home?
What happens if YOU are in an accident on the way home?
Does he have a reliable adult to call in case of emergencies?
Then there is the lovely internet. Even my very honest son, has looked up stuff on Wikipedia and come across some things I'd never dreamed he would see. Fortunately he came to me with the information. I was home with him, standing a foot away when that happened. Imagine what a kid can get up to on a computer in two hours, even innocently?
It's Pandoras box.
So, it is really a tough call. You have to know your kid, prepare them for any event and have reliable adults that can get to him in case of an emergency, immediately.
Kids are kids for such a short time. Independence is great as long as they are ready for it and they are safe.