To most people, the title of this post probably seems rather obvious. However, within certain libertarian circles, usually among the anarcho-capitalists, saying this is akin to pissing in the punch bowl. I understand what the people who use the "Taxes=Slavery" metaphor are trying to say, but I think it's about the dumbest thing someone can say to attract people to their way of thinking.
Messaging doesn't happen in a vacuum and, thus, messengers should be aware of the context in which they are putting forth their ideas. In the United States, with a still-unresolved legacy of racism and chattel slavery with origins that predate the Founding, throwing around the "S-word" so shamelessly is offensive whether it comes from the Left, the Right, or somewhere in between. Given the free exercise of so many rights that we all take for granted, invoking slavery in a contemporary setting trivializes the true suffering of slavery's victims, undermines its very real legacy that remains in our culture, and makes whomever uttered such narrow-minded nonsense look like an ass with no sense of historical propriety. To those of us who can trace our lineage to slavery within four generations and have living relatives who grew up under the racist legal and cultural legacy of American slavery--comparing that history to paying income taxes seems just a bit fucking trite.
Taxes and the government they fund are real problems that need to be addressed by serious people. However, using brazenly lopsided metaphors such as "Taxes=Slavery" amount to nothing more than libertarian Godwin moments.