The crux of the island example is that it's a short-term emergency that deviates from the normal course of human life and that all you want is to survive and get out of the other person's zone of control. The same reasoning wouldn't apply if it was the situation worldwide and you had no place else to go.

I do agree in theory that a similar argument could be made in the situation where the entire accessible universe of property is owned by a group of people who make the cost of land so high that everyone becomes effectively a slave. However, our world has vast amounts of unimproved property that is available for nearly nothing. A friend of mine bought 200 acres in Australia just so he could say he had "a couple of hundred acres", it cost him less than a month's salary. Actually, now that I think about it, it might have been 2,000.

Nobody (but myrkul) wants to live on unimproved property in the middle of nowhere, of course. So we're not talking about a fair share of what nature provided everyone for free but an entitlement to the improvements provided by people. It seems like a much less convincing argument once you realize that.