I'm quite confused about this, since I'm from a place where nearly everybody is a lone child. But what if the 4th grader doesn't have a 9th grader sibling? Lik

I'm quite confused about this, since I'm from a place where nearly everybody is a lone child. But what if the 4th grader doesn't have a 9th grader sibling? Like what do the family do when the 9th grader was a 4th grader? Do parents literally drive them every day to school? Isn't there some kind of school bus system that transports kids from and to their school?