I have two sons, 15 and 10. I don't feel comfortable leaving them home alone for any length of time. I think the 15 yo is old enough to look after himself, but not old enough to also be responsible for his younger brother.
The 15yo feels I'm being overprotective, and that it's a sign I love DS2 more than him, because I'm basically protecting DS2, but not him. (There's logic in there somewhere but I can't find it.)
If I need to go out, I'll take DS2 with me.
AIBU? I really don't know.