I believe I was only 14 years old when I was allowed to stay at home by myself. But I rarely get to stay at home by myself, because my mother usually would have my older cousins to come stay with me while she was working.
When we lived in the city, my parents would not allow me to be alone for several hours. I suspect they didn't want my father's youngest sister to come to the house while they are away. I wouldn't blame them for that reason. My aunt would steal whatever she could from our house.
After my father's death, we moved to the country where my mother built a house next to my material grandmother's house. I think she was comfortable letting me be by myself with a nosey grandmother next door.
As for allowing children be by themselves, I don't know with everything bad going on in this world. Maybe I will allow them by themselves if they can show some maturity.