The problem is that if kids don't eat lunch and go hungry that will negatively affect their ability to learn. As such offering less healthy food that they actually eat might very well be better than healthy food that they don't eat.

If the only meal is literal dog food, hungry kids will eat it direct from the container — a fact I know thanks to a real-life experience of an ex-girlfriend who was trying to be helpful and charitable but had a fit of middle-class naïveté after finding a puppy in a school in Kawangware.