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.
Values and principles are largely subjective. It’s only through overwhelming, collective agreement that some things become so valuable as to be declared human rights, even when it’s staunchly evident they are, e.g. the rights of LGBT people.
I think a lot more political debate similar to this has been voiced and argued about parentless adults being required to pay taxes to support schools. While I think one could easily argue that public schooling is a greater good all must contribute to in order to better society, (though I could easily find you people who would vehemently disagree for some cockamamie reason) there simply isn’t that sort of collective thinking about veganism.
I would not imagine they would be able to counter the point that they themselves had a right to attend school and so it would be a bit rich that they attempt to defund something that they at least had the option to benefit from (and likely did go to school in most cases).