There is so much stuff in school that is more about proving a point than actually accomplishing anything.
For example, in this situation, the food being thrown out is the same end for the food as feeding it to a student. Except, if it's thrown in the trash it's completely wasted. If it's fed to a student, it fills the stomach of said student. Either way there is no food at the end of the day and the school makes no money from that food.
Another example that happened to me today. We had to turn in a short paper about the theme of a book we just read for Lit; it was a page double spaced. We had passed around a rough draft to let other people edit it and we were supposed to make the suggested changes and turn in a final copy today. I had the final copy but I threw out the first draft. My teacher requested the final version and first draft, when I told him I didn't have it but I knew exactly what I changed from the first version and I would make note of it on the paper he said that the first draft was required. Either way, he sees the first draft and the changes to the final version, but one way I get points off and the other way I get whatever I would normally get for the paper.