Somewhere around the age of 10 (I might have been 9 about to turn 10, 5th grade) my mom went to work full time, and my sister and I came home to a parentless house. I didn’t think it was a big deal, but years later I fund out it was extremely upsetting to my little sister who was only 7 turning 8 in 2nd grade. We got along well, and we payed together a lot of the time, but as we got older I think it became more and more lonely for her maybe? I went off with my friends a lot in 6th grade and older. I usually spent afterschool at my friend’s house not vice versa so she was alone and still very young, and I think she didn’t like it. Generally I think it is harder for younger kids anyway, they want to be with their older siblings geberally, just by design.
I was able to cook and do everything for myself. We played in the street with neighborhood kids, road bikes, or just watched TV when we were really little.
I also started babysitting when I was 11 like @augustlan. Funny, when I first turned 11 my mom wanted to leave us home alone at night if they went out, which was very rare my parents went out on their own, or to a party, maybe once evry couple of months. Anyway, both my sister and I wanted a babysitter to be with us. I don’t think I was afraid, I just think I liked having a teenager there. We would stay up and watch later shows, and the babysitters were always fun. Then when I started babysistting my mom put an end to it wanted to save the money.
My dad and mom both said they weren’t worried about leaving us along after school. My dad said he never even for a second thought it would be odd to leave us alone after school. Literally when I asked him about it this week, he said he had never even considered it was a thing for some people. He said he grew up like that, his whole neghborhood did, it was normal to him.
I think it just depends on the kid whether it is traumatic or not. I think most states have laws against kids being left alone under the age of 14? Or, maybe that is for a long period of time?