Subsidizing expensive tastes doesn't strike me as discriminatory.

Would you say the same if they refused to serve kosher/halal meals for Muslim/Jewish patients?

UK law protects some philosophical beliefs equally to religions. (what qualifies is a bit of a mess as it's all case law)

(On a practical note, I imagine it's easier for hospitals to just serve vegan food for anyone who is vegetarian/Muslim/Jewish rather than have specific kosher/halal meals)

Actual yes since I think all religions are illogical…

Religion tends to be more constitutive to a person's self-identity than purity signalling dietary trends.

Setting aside the fact that there are multiple very old, very large religions that are nearly or actually vegan (e.g., Jainism), or that people raised vegan can't easily digest meat or animal products, why on earth do you feel that you or a hospital worker are qualified to determine the beliefs making up someone's identity, when you know absolutely nothing about them?

It took Western government institutions hundreds of years of violent conflict to embrace religious tolerance. I don't recall any major intense violent conflict being fought over dietary preferences.

Vegetables, legumes, nuts, and grains are not expensive, and veganism is a protected class in the UK.

Yeah but when you're mad at a nation not force-feeding meat to vegans you have to come up with some reason why the vegans are bad.

Having a separate option is however not free.

Actually the subsidies mostly go to diary farming. Vegan food is cheap to produce but mostly not subsidised. This, plus the (no) economy of scale makes the shelf prices sometimes slightly higher, eg soy milk vs defatted milk.

Lol at eating just plants as being expensive. You do know where animals that are eaten get their food right?

Mostly from plants that humans can't or at least wouldn't want to eat.