I think this is a wrong point of view for the entire issue. After all, one of the primary reasons people form societies - and societies as they grow form governments - is to prevent the oppressor scenario you describe. You can say that maybe every generation of adults should decide again if they like this idea, but that seems a bit inefficient.

Consider instead a different question - what authority your parents have over you when you're a child? After all, you haven't agreed on anything. Aren't they an oppressor, that often forces you to do things (like eating broccoli) against your will?

The parents/children example is an interesting one, and parents are usually given authority over their children until the child reaches the age of majority. The problem with this reasoning is that there are a few possible conclusions (which I can think of):

1) The state has authority over its citizens until the citizens reach a certain level of capacity. As an adult who makes most of his own decisions, I believe I have a level of capacity which allows me to make good decisions without a state. This seems reasonable, as the state has declared me "eligible to vote", and perform other tasks significant to the state, which appears to be an endorsement of my level of capacity.

2) The state is our eternal guardian, and has authority over all of us forever, thus North Korea and other totalitarian states have the moral authority to oppress and direct their people in ways that seem wrong, because we are but children.

The other problem with this reasoning is that it doesn't really define what gives a state this authority. If I declare my own state "The Kingdom of Nickff", and invade (a portion of) Canada, I have the same authority as the previous government, though I may be 'cruel' and 'despotic'.

And you haven't explained why I don't have a pony.

You don't get a patch of sovereign land as a birthright. That's never how it worked, anytime in history. You can play by the rules here, you can go someplace with different rules, or you can go someplace with no rules. Plenty of rural areas in the 3rd world with no effective government presence.

I'd also consider the whole dynamics over the course of history. Many times people wandered into uninhabited lands. They always eventually ended up forming societies and governments to regulate the commons and avoid infighting. This seems like a feature of human nature.

Hey, it's not like they got those "uninhabited" lands for free, unless we're talking about the first migrations out of Africa. They had to pull themselves up by their bootstraps and genocide their neighbors before they got any uninhabited lands. Now these anarcho-libertarian kids want to just get lands without any of that hard work butchering people. Sigh.. kids these days. No work ethic or respect for history.