True, but if it isn't a known allergy, then it shouldn't be catered for with a ban. And in fact, the Anaphylaxis Campaign only advise total bans for the most severe allergies, because it teaches the allergic child to be vigilant in all situations.
Surely it should be the same for religious or ethical food avoidance?
My DS3 is anaphylactic to pineapple and kiwi on ingestion, but I wouldn't expect a ban on those, as it is only when HE eats them that he has a reaction. He is also anaphylactic to peanuts, tree nuts, lentils and chickpeas. But again, he only reacts to having eaten traces of them, so I wouldn't expect them to be banned for the other DC's.
However, his anaphylactic reaction to the smallest traces of Cow's Milk Protein is so severe that if one pinprick drop of milk, yoghurt, cheese or chocolate makes contact with his skin, not even having to have eaten or drunk it, he goes into anaphylaxis and could die.
The other severe, life threatening allergies I wouldn't expect to be banned for other DC's in a Nursery environment, I would expect the staff to be vigilant.
Dairy in all its forms, though, a ban is necessary.
So IMO if the majority of his life threatening allergies can be managed without banning those things for other DC's, I see no reason why religious or ethical food avoidances can't be managed the same way.
It's only because his allergy to dairy is SO severe, and is even from secondary contact like a pinprick drop on a table that he rests his arm on, or someone opening a yoghurt lid across the room and a drop of yoghurt flies and hits him causes anaphylaxis that a ban is necessary.
Maybe that's why I can't see the need for bans on types of food for ethical or religious reasons?