Eating a parents food is a little more understandable, though still not something a kid should do without permission. Eating a teachers food, is down right actual stealing. It is different even if the teacher is supposed to act like a parent, though I haven't heard of that being the case, if anything teachers are restricted from acting like parents to the children.
They may have some legal burden, but it doesn't mean it should be treated exactly as if they are the parents in every situation.
But I did say it was fair that the teacher got in trouble, just thought it odd initially that it doesn't mention the kids repercussions, til I thought about the hurdles involved in writing that bit of the article and assumed they just didn't bother.