We lived a 10 minute walk from school, about 14 kids in our cul-de-sac went to our school, so we'd all meet up and walk together (no adults). There was only one small road to cross, then the main road which had a road patrol crossing. We were aged 5-10.
In intermediate my house backed onto the school, so not an issue.
For high school I had a 2.5 hour bus ride there and if I missed my 5.45am bus I had to hitch hike to school (12-16yo).
My kids school is in the middle of nowhere, so no, I won't let them walk, but if they were going to a nearby local school I would consider letting them walk with neighbours as a big group, depending on the neighbours and depending on how sensible I think my kids are.