Even if cafeterias are subsidized by taxpayers, if some kid’s veggie burger costs the same as my kid’s hamburger, there is no negative economic impact to offering the veggie burger.
If you want to end subsidies for school lunches, I am on board. I see no reason for them. But, they are not really relevant to whether it makes sense to offer a veggie burger that cost the school, for argument’s sake $1.00, next to a hamburger that cost the same.
Economic ignorance, the cost of maintaining more and different is a cost as well as the special prep, are do you want your veggie burger fried in cow grease. There would never be a time when there was not additional special cost.