It's 500 people on a tiny island demonstrating that 500 people don't need a government to function as a community. They say they can just make agreements between themselves, which is the purpose of the government, to solve that problem at scale. If one of them needs help I'm sure the rest of them would try to help, which is what wellfare is when millions of people are involved.
I'm guessing that if I go there and start a business dumping waste on the island (which would be very profitable for me, it is increasingly costly to get rid of waste in most countries because of the stringent regulations) the people there would have to learn what taxes and regulations are for.
Anarcocapitalist and Libertarian frameworks can still have methods of dealing with such problems. At best they have laws, contracts, and private police and you would be sued. At worst, they might shoot you.
I have a feeling that my waste dumping company would have a better chance at owning that private police, and the people making the laws. And the media. There would be many ways to distract and exploit the people. Creating uncertainty and a conspiratory political culture would capture most by offering a simplified, stabilized world and a sense of community.
Exploiting distrustful people is the biggest industry there ever was unfortunately, including causing them to become distrustful, uncertain, isolated. It's how terrorists are made. It's how voters who vote for political extremism are made.
Ironically all of this would only work at scale, 500 people on a tiny island would be harder to control, I'm guessing due to their closeness, or quality of their interactions. You could play them against other communities, but not against each other. We have a lot of brain stuff to ensure the viability of small communities. It's all built-in, taken care of. The problems only start at scale, when everyone is isolated. You have to be inventive at scale.
You kind of trivialized this by saying that if there is no problem there is no need for a solution. But in real life we are interdependent in non-obvious ways, and need more sophisticated solutions than shooting each other.
The need for sophistication is obvious. Protecting your land is an easy case, but wouldn't you want to protect your future interest too and have a say in what I'm allowed to do on my own land, if that is something that could permanently damage the ecosystem in the long run. Or if I start selling unsafe, addicting products, the libertarian approach would be to let everyone decide for themselves, and subsequently fend for themselves. But isolated people are more suspectible to manipulation, and children too, everyone can be. The libertarian approach would be to leave people behind in the name of self-governance.
The question isn't even should self-governance be our goal, the question is whether it can exist at all. It's kind of an oxymoron, because nobody can protect their rights just by themselves. Building a trust infrastructure is perhaps more important.
You need a constitution to define rights and to stick to it.
It is a contract and can't be whittled down or imposed on by public opinion. If own the rights to land, you can do with it what you want. If you want to put a garbage dump next to a playground, that is their problem if you aren't physically hurting them.
Libertarians absolutely believe in laws that uphold rights, and legal precedent describing how rights interact.
See this is where that libertarian-paradise-town in New Hampshire went wrong: if you put yourself on an island, you are less likely to be overrun by bears.
I'm guessing that if I go there and start a business dumping waste on the island (which would be very profitable for me, it is increasingly costly to get rid of waste in most countries because of the stringent regulations) the people there would have to learn what taxes and regulations are for.