My elementary school and middle school both did not have cafeterias, so the only option was to brown bag it. Plus the elementary school had lunch inspections daily, as things like pop, candy, potato chips etc weren't allowed.
Our highscool cafeteria was amazing. The food was cheap (2 bucks for soups, salads and sandwiches, 4-5 dollars for entrees like pasta dishes or meat with potatoes and veggies) and it was also all made fresh daily. Instead of paying lots of money to staff and cook the food, they allowed the local college to use their facilities to run their culinary arts program. The HS students got cheap and healthy food, and the college students got their training. It was win win.