Yep.
Also, liability/litigation.
I would think pedos would be a much smaller problem these days with gadgets like a watch or something that can track a kids location and velocity any time. Program the kids watch to alarm the parents phone if he is moving at greater than 15mph any time the parent is not in proximity. If it is expected and ok, silence the alarm. If not, parent can send a signal the kid can feel on his wrist. Two squeezes of a button means ok. No action or just one squeeze means trouble and start tracking
It may have to do with sidewalks. I walked to school in NYC from K-12. My sister did walk with me till the third grade. In rural Maryland we lived too close to the school for my children to take the bus. There were no sidewalks, no crossing guards, no school zone drop in speed limit. I told the town my daughter was handicapped and couldnt carry books well. Their response was to send her to a bus stop a half mile in the other direction. The amazing part was that the towns mayors daughter was hit by a car and killed walking to school along the road they wanted my daughter to use. We decided just to drive her to school. Maybe, its cheaper to run busses then build sidewalks and use crossing guards. A lot of parents abandoned the school buses after a middle schooler was caught performing oral sex in the back row. A lot of parents didnt want their young children on a school bus.