Give us an example of anarcho-capitalism failing.
It is hard to establish because I think that you are simply going to deny that those examples are relevant but in general, periods of anarchy are quite common across Africa and there are many places in the middle east that are in constant flux with common periods of anarchy. They don’t last long and they are all short lived for the same reason – someone with big guns moves in and installs themselves as the chosen leader (aka: King). There are even some examples in the Middle East where there is a semblance of anarchy as far as governments go but each are is essentially ruled by the local leader who does as he pleases to the people there. We dealt with these groups a LOT during the invasion of Iraq and Afghanistan because they were essentially the local governments headed by the eldest male. That, in general, was VERY close to anarcho-capitalism but you still ended up with oppression because the eldest male essentially had the powers of a King. In that society, only the top flourished while the rest were subjects.
The idea that anarcho-capitalism can thrive flies in the face of that because capitalism never really exists in those areas because the market there is never truly free. Instead, it is quickly taken over by a local warlord until he can be disposed where another short term anarchy exists before that new leader gains control. The idea of private armies providing security is a nice thought but in general unworkable. There is much more wealth to be made in the short term from plunder than there is in security so that is where we end up every time.
Essentially, at the end of the day a lack of official government does not mean that there will be no government. We like to think that is possible but the world shows that someone will take over that slot. A limited and controlled government might not be ideal as anarcho capitalism is the ideal but it perfect is simply not possible in the real world. With that in mind, that limited government puts controls on the subjugation of people through force.