Earlier quoted context omitted.
Going through the school system (private pre-K/K and public) was really what changed my kids' eating habits. Once they get used to the school nuggets and pizza, it's hard to "unlearn". They were more diverse eaters as young kids and ended more picky and narrow in their food choices. It's why pizza is the staple of every kids' birthday party.
I believe this is a difficult problem for schools. They need to have food that meets the standards (as they are defined), appealing enough to 6 through {age} range to have them eat it, something that can be prepared with relatively low skill demands, and something that can be prepared easily in the quantities needed with the kitchen staff provided. That really gets down to reheated chicken nuggets, pizza, and other c…
Deciding that we need to serve food at a minimum of cost with a minimum of staff who is minimally trained according to a minimalistic nutritional guidelines, and charge children for the privilege of choosing to eat, and you aren't getting a feast full of fresh produce.
Japan is a decent model in making meals more communal and spreading the labor requirements around to students so that staff can focus on back of house work, but it starts with a higher budget basis to start with, makes meals mandatory, and provides significant subsidies.