Initiating a legal battle is not for the faint of heart. Few want to tangle with authority, and the kind of people that would implement + enforce such a thing (e.g. school administrators) are notorious for being petty and inflexible. Moreover, they often have lots of legal backing for their actions (due to "in loco parentis" status) that are hard to pin down.

Most parents don't have the resources for such a suit (or defense), and most students probably don't want to risk getting suspended/expelled or sent to a different school for being the one who sticks up for their rights.

As others said, no one cared enough to get into a legal battle.

And to be honest, the buses weren't bad. Particularly in the winter. You would have been crazy to want walk instead of getting picked up outside your house and dropped off at school. You could get a school permit to drive to school at 14 too (I drove to school in 8th grade), so kids in high school really didn't care about walking.

I also never heard of anyone actually getting in trouble for walking. It was probably just an empty threat, but it was meaningful enough that no one ever tested it.