What of observed human history gives you any hope that such a thing will happen?

All of these systems function well ... "in theory". Even the ones you may not agree with. Socialism and communism are perfectly fine theoretical systems, until you introduce humans into the equation with desires for power, wealth, etc.

I have seen no hint that Libertarianism is somehow above this and will be the panacea. I also have no idea how you come to the conclusion that collusion will not be a problem in a libertarian world.