Taxation can be theft or violence if you claim that all the government-issued paper you manage to get your hands on in the context of said government is legitimately and naturally yours. That's not that easy of a case to make decisively I think.

When living in a society, you are indeed forced to cooperate and that's inevitable. Taxation in the context of democracy is the best practical model we have so far. If we get a better one, I would love to get rid of it. I don't like my taxes going into the pockets of corrupt politicians either. Just explain to me how we get rid of it all and end up with something better.

If you claim that modern people are less free and more oppressed than feudal peasants, I really don't know what to say. I'm sorry to put it so bluntly, but that's ridiculous.