What others have said about this being out of his control is spot on, and this treatment will do nothing but make him resent the entire system, his parents included.

That said, punishment only works in the short run...as does his prettier sister, reward. We humans are not dogs or pigeons...most of the science behind this system of behavior mod has been done on animals. While humans do respond to both in the short run, in the long run this system only teaches them to either, in the case of punishment, not get caught; or in the case of reward, expect greater reward after a while.

The answer to this problem with the boy would be for the principal to take a few extra minutes out of her day to talk with the parents and find a work around if that was indeed what was necessary. Your car won't work and you live within a mile of the school? Maybe we find someone to carpool with. Maybe I, the principal, come and get him myself. Are you having trouble getting around in the morning with osteoporosis? Maybe your husband can fix lunch for the boy before he leaves for work? Maybe you get everything ready the night before? Maybe you go to bed a half hour earlier and get up a half hour earlier? And on and on...

Punishment, in this case, was probably supposed to be a wake up call to the parents to fix the issue. This only puts the boy in the middle and actually punishes him. Frankly, the principal is just as much to blame for this. If tardiness was a serious issue, serious enough to do this kind of crap to young students, then she should have had several communiques sent out to parents well ahead of the time she'd start doing this bullshit. She should have had meetings with parents of problem children. She should have taken some extra steps herself if she was going to lay down the rule as being an important aspect of her school's culture. As it is, she appears lazy and a little bit cruel.