No question. It’s wrong not to return shopping carts. That said Moisha’s offers online ordering and delivery, which is much better experience than looking for parking, looking up and down the isles and shlepping your own boxes from store and loading and unloading. The deliveries come in boxes and arrive at your door. I prefer this convenient service.
The principal is wrong, this is a high school not third grade. This is what causes kids to hate rabbonim. We are dealing with a student that owns a phone. As long as he doesn’t take it out of his pocket or it does not ring / vibrate, the school does not have a right to search his pocket.