Veganism without the Non-Aggression Principle is meaningless.

The milk, the farmer & the 'self-love'

So what does make taking milk from the cow violence?
Simply by the leak of consent, stealing her baby away and such. Most vegans know this. For who doesn't a calf doesn't stay with his or her mother simply the farmer doesn't benefit from a mother feeding her baby. This is where a life of suffering and exploitation starts. Farmers will say they love the cow, but that is simply compared to the charssidic learning of fish-love.

Farming Humans

Now, what makes taxation violence?
Nobody ever asked you if you wanted to be taxed, you just grew up in a system with it. The same as the cow who was born in a system that she was meant for farming milk. You are born in a system where you are taken away parts of your property and assets without any form consent, if you are trying to avoid paying taxes you are taken away your freedom and go to jail at gunpoint. Basically, this is where humans are farming each other.

The NAP

Now nature is complicated and I am not able or willing to tell a lion, wolf or bear that he/she should respect the NAP. But some of you don't know what the NAP is.

The non-aggression principle (or NAP, also called the non-aggression axiom, the anti-coercion, zero aggression principle or non-initiation of force) is an ethical stance which asserts that "aggression" is inherently illegitimate. "Aggression", for the purposes of NAP, is defined as initiating or threatening the use of any and all forcible interference with an individual or individual's property. In contrast to pacifism, the non-aggression principle does not preclude violent self-defense. The NAP is considered to be a defining principle of libertarianism.

Supporters of the NAP often appeal to it in order to argue for the immorality of theft, vandalism, assault, and fraud. Compared to nonviolence, the non-aggression principle does not preclude violence used in self-defense or defence of others. Many supporters argue that NAP opposes such policies as victimless crime laws, taxation, and military drafts. NAP is the foundation of libertarian philosophy.

Of course, most of these things aren't any worried for most species but for humans it is and most vegans don't believe in punishing victimless crimes as it is. But this is a human moral stance. We as most advanced species in our tools or to put it from theological perspective us who were created in the image of g'd, should be the one responsible for making the best world for all them possible. It doesn't matter if you are religious or an atheist, agnostic, secular. None of that matters towards the simple ideas of liberty and a major integration of the NAP in it.

From school to real life.

Now the people that know me know I'm not strictly libertarian but a classic liberal. Strictly meaning I do agree until society is ready for a change towards a real functioning society without government, it's okay to have a small government that does provide security, infrastructure even school & healthcare. But that does allow a free-market and competition even against state-owned businesses. For example currently in Europe public transportation. And simply reject monopolies or cartels by law.
Which you find good examples of in the Dutch-Healthcare insurance system and the public transportation which is exploited currently by the company NS b.v. But I also found a video on youtube that explains why state-owned business does a lot worse than private investments. As we can learn from history.

As we can see in the video violence has a lead to a lot of waste. A waste of federal tax dollars. The violent which start out as a solidarity policies which tax usually sold as turned into a cartel with private profits, the solution here was simple less government. Miles of unnecassary railroad built and the infrastructure that was set wasn't set the provide to get people from A to B as quickly as possible but to ring every penny out of it.

And from the vegan perspective, this is how the exploitation chain happens from involuntary payments.