School goes as far as preventing the kids to eat their snack if it's not a fruit or a vegetable which I find excessive, as many healthy snacks exist today that still contain some carbs

I don’t even know how to parse this statement. Fruit has tons of carbs; so do may vegetables.

And people have such varied dietary needs, I find it shocking that a school would dictate what foods are permissible.

Curious where you’re located, generally.