I think school meals should be compulsory for all primary children.
I read this thread, and remember that at my primary ALL the children ate school dinner - apart from one or two who went home for lunch.
However it was much more civilised than the canteen style they have now. Everyone had a designated table, and there was no choice of food. You had dinner. It was always properly cooked stuff too, like meat pies, and sponge and custard for pudding.
DS is 15, and has been to three schools in his primary years. Only one of them had decent meals.