School dinners are not allowed to be pizza/chips all the time. Pizza bases must be wholewheat. They are allowed to serve oven chips once a week and can only serve potato-based carbs twice a week. There must be two portions of vegetables and most schools also serve salad. School dinners are not allowed salt to be added to the recipes. They can't have ketchup unless it is home-made.
In your school perhaps. This is not true of all schools. All three schools on my sons schools campus serve Heinz Ketchup everyday,Sausages rolls, Cornish Pasties, Bacon Sarnies and Chips are available in the canteen everyday (except Friday)...they also have salad and healthy options available every day as well....they have coke machines, vending machines with crisps, chocolate etc freely available have no policy on allowing or disallowing children to visit the chip shop or newsagent next door either.
Hence he takes a packed lunch and express instructions that if we find out he has left the school grounds at lunch time without good reason then he will lose privileges.
The only thing my sons school enforces (not the other two) is meat free Friday, where the canteen serves only vegetarian options.