By opting to not leave the nation upon, say reaching the age of 18, are you not agreeing to an implicit contract by virtue of your residence and use of its services?
No, because that would assume that the government owns everything.
Here's an example for you: let's say you were born in my household. Even better, let's say you are my child and were born in my household, and I demand payment from you to continue to live there. You counter by stating that you own your own bedroom because you bought it from me. That's fine, I say - you own the space inside the walls, but that doesn't really mean you can act with impunity and not pay me a fee to continue to live there.
You are free to leave.
Basically, you're over interpreting the concept of land ownership to mean that you can operate your own sovereign domain within another sovereign domain. Life does not really work like that - unless you're the Catholic Church and your host is Italy.
Again, you're assuming that the government owns everything. I'm not living in Uncle Sam's house.
Tell me, do you fantasize all the time that you are that farmer? Do you fantasize that you were here before the US government? Or wait - maybe I have it wrong! Let me guess - that home you own, the one with the HOA - you've owned it for several centuries.
Don't get personal. I don't have any such fantasies nor did I imply I was that farmer. It was meant to illustrate the
facts of history.
You see, you aren't that farmer. When you bought your house, not only did you enter into an agreement with the HOA, you decided to continue to be a US citizen and resident of the US in addition to being a resident of the HOA. And you decided to continue to pay your taxes, instead of moving out of the country.
By continuing to live in your house instead of leaving the country you are agreeing to follow my rules? No, because I don't own your property. The government doesn't own mine.