That's not the problem. Wave a magic wand and have all cities walkable and bikeable and you'd still have school busses.

I suppose we could wave more magic wands and say "ok, everybody with kids has to live in a city whether they like it or not" and wave some more magic wands and eliminate all concerns about crime or other dangers, but if we're going to wave this many magic wands maybe we should just wave one that makes it so children don't need to go to school at all because they are all magically educated already.

Much of the world operates without dedicated school buses. Kids use public transit or walk or whatever, just like other residents.