Some Chicago public schools ban bringing your own lunch to school.

The Chicago Tribune reports:

"Nutrition wise, it is better for the children to eat at the school," [school principal Elsa] Carmona said. "It's about the nutrition and the excellent quality food that they are able to serve (in the lunchroom). It's milk versus a Coke. But with allergies and any medical issue, of course, we would make an exception."
Carmona said she created the policy six years ago after watching students bring "bottles of soda and flaming hot chips" on field trips for their lunch. Although she would not name any other schools that employ such practices, she said it was fairly common....

Any school that bans homemade lunches also puts more money in the pockets of the district's food provider, Chartwells-Thompson. The federal government pays the district for each free or reduced-price lunch taken, and the caterer receives a set fee from the district per lunch.

So is it for the benefit of the children or somebody else? Note that the kids think the food is bad, and the competition is crushed, so there's no pressure on the food service to make something the kids would prefer to whatever is they bring from home. But the schools' providers are required to present healthful foods, and maybe it's not fair for them to have to compete with whatever enticing treats the kids get bring in from the outside.