We lived in a city where high schoolers take public transit and that worked well for them, but the district could never hire enough drivers for the elementary and middle schools. Even with the drivers they had, they had to stagger school start and end times so that buses could do multiple routes. Some schools started at 7 and others at 9. Then the problem you highlight comes up, that there are only a few hours between shifts, so it was harder for drivers to have a second job. Many drove Uber between.