Food restrictions are a part of school these days… it becomes a topic at the beginning of each school year whether there are any nut allergens…. if so, no pb&j.
But it’s not just nuts…
My kids have attended Gateways summer school program… it’s a secular, educational enrichment program. It’s held on the campus of a private Jewish school (but not run by that school). So lunches can’t have any meat to comply with the kosher campus. http://www.gatewaysschool.org/faq.php#lunch
This is just part of being considerate of others. You could ignore this… but that would be kinda assholish.