If they’re going to feed kids at all, it might as well be healthy food. I hear the menu at a private school here is quite nice and healthy compared to what the public schools serve.
I went to public schools back in ancient times, and we always had appetizing and healthy lunches. My son’s school has been serving things kids like to eat, but are not particularly nutritional. For example, their idea of an entree was nachos, and their idea of nachos was corn chips and cheese sauce. That’s all. So this year they went the “spinach tortellini and squash” route, and my son says most kids throw it away.
None except the most expensive private school is going to be able to serve sushi safely.