I've wondered something similar....

If a minarchist like Ayn Rand were here, she'd probably say that there's no objective way to determine whether an economic transation is fair or unfair. IOW, if two parties consent to a trade, then both benefit, and a bystander has no right to interfere.

Although I think, if one goes this far, why not just have full blown anarchy? Economic power and political power are two abstractions of the same thing. I'm not sure one can really distinguish the two except in theory. Even in the U.S. it's pretty easy to convert one form of currency into the other.