is this an americabrained comment? here in sweden, and this is not some urbanist paradise, kids can absolutely get to school on their own, whether that be walking biking or taking public transport.
it's in fact bog standard for kids to take the bus to school in my town, to the point that you really want to avoid their travel times because buses will be jam packed with annoying children.
In some states it's illegal to leave children of a certain age unsupervised. I think it's 11 and below here? People do it anyway and no one's looking to prosecute, but it's a thing.
I can't speak for every municipality in America, but the elementary schools around here do not allow kids to walk or bike to school. Either that, or every single parent, no exceptions, disallows it, because I've never seen a child that young coming into or leaving the school on their own. FFS, when I used to pick up my stepson, same car every day, the teacher had to put their hand on the roof and look me in the eye through a rolled-down window. That was literally the rule.
So like I said, "some of the younger ones aren't mature enough or raised independently enough". It sucks, but it's true.
I have an 8 and 10-yo. They love my house because I allow them freedom. We went to a huge camping place to get married this weekend, local outfitter sort of thing. I gave them some instructions and warnings, cut them loose. Their helicopter mom would shit her pants if she knew they walked all over the woods alone.
(And of course we got the usual comment below crying about capitalism. I'm not sure if these people expect that no one works for a living, or they don't do it on a coordinated schedule, or what.)