If you need proof that Anarcho-Capitalism doesn't work, just play Eve-Online for a year in 0.0 security space.
Killing people and blowing up ships is completely irrelevant. The game could be about planting trees and picking flowers, and the same principles would apply.
What it comes down to is this: is the general populace comfortable enough to engage in open economic activity?
You can see that there is a lot less confidence in the US and the rest of the world, in large part due to various stupid decisions. But this doesn't prove that anarcho-capitalism works. It just shows that corrupt capitalism doesn't work well either.