You are right, there are many reasons. I know a boy that would not eat while his parents were going through a nasty divorce- he really would not eat. His doctor told his mother to feed him ANYTHING he would even attempt to eat- candy, chips, you name it. When he started eating again she gradually altered his diet back to normal. So if food police had switched his lunch for a cafeteria meal they would have been going against his doctors orders.
You know what’s in those chicken nuggest they serve in schools? Not chicken ....