Elwar, to date you and I have seen eye to eye on everything, but the title on this post pisses me off!
Yes, I know what you mean, we all experience a harmonic anarchy most every day. When I went to the grocery store today, I followed the stores rules and the society around me followed etiquette and everything went smoothly with no state intrusion whatsoever. Harmony without rulers. Check.
BUT... To state that the "World is anarchist" is spitting in the face of freedom! For the world to be anarchist today, I'd think there needs to be no democide going on anywhere, no prisons full of people who aren't real murderers, no corporatism nor cronyism, and of course no freaking tax farms with arbitrary borders!
It's kinda insulting, at least the title is. You're almost denying the sacrifice of everyone who ever died from democide.
Setting that aside, I've got one other major beef with your OP. You clearly are making a strawman argument with what your vision of a world in anarchy would be like during this part:
At that point you face a choice. Are you more powerful than that dude? Can you continue drinking without him interfering? You may be bigger so you stand up to him telling him that you are a free person that can do whatever he wants. The dude disagrees and pulls a gun. In this anarchist world, survival of the fittest prevails. You are subject to that person's whim because he has more power than you do. He can now use his gun to take you prisoner for as long as he and his friends think is right in their own eyes.
In a world without rulers, there would be other pressures and circumstances that you are not taking into consideration here. The scenario would go very differently indeed if it escalated past politeness.
For one thing there is a thing called Assurance. For another, there is Private Security.
That is what I was talking about when talking about you and your friends having enough power to make the power of the other moot. Call them friends, call them paid security or whichever.
The statement of an anarchist world goes along the lines of being born with inalienable rights. That is just something you are born with, everything from there on is thrust upon you such as the prisons, taxes, borders, etc.
But in a world of survival of the fittest, those that organize their protection win out. It just so happens that this has happened. The US government has amassed great power, and they are more fit than me or you in this world of survival of the fittest.
That is why I am saying that just like in the world of currencies, the Federal Reserve has reigned as the ruler of money in the US. The solution is not to end the Fed or destroy the dollar. But to build an alternative that is better. I believe that is also the best way forward when dealing with governments. Not to try to end them or bring them down, but to create a better alternative based on voluntary decentralized power.
In such a way that the 18 year old scenario would be more like this:
You leave home at 18 taking along a bottle of champagne to the local park. You go to take a drink and a guy stops you.
At that point you face a choice. Are you more powerful than that dude? Can you continue drinking without him interfering? You may be bigger so you stand up to him telling him that you are a free person that can do whatever he wants. The dude disagrees and pulls a gun. He tells you that the park was created by the Conservative Prohibition Club and one of their rules for the park is that nobody can drink alcohol on their property. He tells you that he belongs to their security force, CPC security and that he has jurisdiction on all property belonging to that club. But he tells you that the Liberty Alliance has a park just down the road that allows drinking whatever you want. They have a Liberty Alliance security force that is just as powerful as the CPC security so they leave each other alone, besides both security forces get partial funding from the Stop the Violence Association who's explicit goal is to prevent security forces that they fund from interfering with one another or face the loss of funding.
You move along to the Liberty Alliance park and enjoy a good drink with like minded people.