But what's the alternative?
Way back in ancient history when I was a child schools didn't provide lunches except for one day a week when mother volunteers would come in and cook food for those who would pay for it. Everyone else brought their own food from home as they did the rest of the week. Usually we had a sandwich, a piece of fruit or some carrot or celery sticks, and something sweet (often home baked) for dessert. We would have either fruit juice or milk, which might be in a thermos bottle or a small carton.
However so many mothers now have jobs outside the home that there's not much chance of having enough volunteers to cook for a whole school and health departments probably wouldn't allow that anyway. Some kids do still bring their own lunches, but those usually contain pre-packaged food that's probably as unhealthy as the things sold in cafeterias. And low income kids count on school lunches to get adequate food.
With budget cuts in many school districts (especially in California where I live) selling school lunches might be a way to make a profit, but chances are the programs may be discontinued in some places and more families will be cutting corners by making lunches at home instead of buying them.
At least now we have good freezers so it's possible to make enough sandwiches for a whole week at a time.
Peanut butter and jelly, anyone?