If you’re a vegan in the US but you pay tax, part of your tax contribution goes toward livestock farming subsidies. So in effect you are forced to support unethical treatment of animals.
So I have to wonder-- have vegans attempted to fight for the right to be fully vegan and thus requested to opt-out of those subsidies? In principle, it seems a vegan should be able to tick on a box on their tax forms saying “I was vegan this whole tax year” and the result should be a tax credit that reimburses their share of the livestock subsidies the gov pays every year using public money.
(Religious) pacifists are required to fund wars under this system already. No one would argue for higher protections for vegans than religion, which is already better protected constitutionally in the US. So unfortunately I think this is a non-starter for legal determination. Morally speaking, you could have that conversation, but it wouldn’t slot in to our existing framework as it stands.