I think there is an important difference to make between a couple of things you name here.
On the one hand, you say people have no other choice to work, and therefore they are slaves.
On the other hand, we have little choice in paying taxes, since the state forces us to.
What's the difference? Well, we are NOT slaves because we have to work. We have to survive either way. Even if there were no work at all, we'd have to survive in other ways, like hunting and living off the land. This is not slavery, this is simply survival.
The thing that makes us slaves, is the state. We are forced to fund that institution regardless of whether we agree or not. That is what makes us slaves. Having to work to survive does not.