You can't extract your existence from the country you made your money in. You used and benefited from the resources of the system, and those resources cost money in a primarily capitalist system. I would prefer a system where people (like you) can opt out and go somewhere else before they see any benefits (or repay the debt directly), but that's not yet possible.
We're left with this system that works well enough for most people until something better comes along. Until then, free riders are a drag on the system and need to be reminded that they don't exist in a vacuum. I don't support executing or imprisoning public service debtors. My representatives are generally anti-government, so I don't even need to tell them this.
I can't extract my existence from the country not because it's technically impossible, as you claim, but because state prevents me and others from doing so. If I wanted my kids to go to a private school or if I wanted to homeschool them I could do it, but I would still have to pay the tax. If I wanted to use private roads all the time, I would still have to pay the tax; additionally, states do not allow private roads in cities, for example. And in many other areas of economy, state acts as a monopoly, preventing others, either economically or by force (licensing, for example) from entering the market.
Thus when people tell me "but you have to pay taxes because you use this service government provides" I wonder how come my ISP didn't come to me and said "we will provide you with internet access from now on and you will pay us this much money or you go to jail". States don't ask or offer, they order you.
Finally, when people talk about social responsibility and how we should be grateful to our teachers, for example, it's also very misleading. Yes, I might be grateful. My parents paid their share of taxes that went into teachers' salaries. What more do I owe them and why? If I'm grateful to Steve Jobs for inventing iPhone, or Khan Academy for awesome educational videos, or Wikipedia for a great deal of information, does this mean I should be paying them for the rest of my life and go to jail if I refuse to do so?
We're left with this system that works well enough for most people until something better comes along. Until then, free riders are a drag on the system and need to be reminded that they don't exist in a vacuum. I don't support executing or imprisoning public service debtors. My representatives are generally anti-government, so I don't even need to tell them this.