There is apparently a phenomenon in the US now, where parents drive to the school individually to pick up and drop off their children at the beginning and end of the day. Some people I work with even take time off from working to do this. When the parents descend on the school each day there’s insane traffic, cars lined up for miles, all idling their engines. What happened to school buses?
This can depend on a lot of factors, but the biggest is often time. School busses usually can service the overwhelming number of kids in their district, but for some kids that route can add an extra hour before and after school. For kids with after school activities, that could be a non-starter.
Doesn’t seem to me like a mile-long queue of cars would reduce that time by much, especially if there is some actual driving to do too before entering the queue and after leaving it.