Well, yes, the incapability of the Libertarian bloc to comprehend that the system isn't perfect, and not everybody (and in fact most people) is just so awesome that they can go from nothing and then end up super-rich.
Blah blah blah Just World blah blah.
Also, I'm not sure how this "taxes are oppression" thing works. You like to drive on roads. Government builds roads. You pay taxes, you use the roads. How is this any different from buying something from somebody, except on a large scale?
The idea is that they have no choice to "opt-out" of the system, thus that they are forced to pay into a system that they may wish to have no part it. It's an argument familiar to some from the healthcare debate; they fail to realise the fact that it's largely cutting off your nose to spite your face.
Another's the postal service. It's redundant with several private companies that do a better job, sometimes for less money.
they do better because they are inherently better, or are they kept good due to competition from the public sector? I admit that I have no idea.
I do think that rural customers will get shafted, since it will generally be a loss to expand your postal service beyond areas with a dense concentration of people. Of course, "getting shafted" is all a part of the private sector experience.