It was inspired by this mural I saw when I visited Chile. There was this whole saga of exploitation by outsiders, terminating with a brown person shoving another brown person's hand into a blender and accepting a credit card from a white person (it's right outside the street art tour place in Valparaíso). It was pretty striking to be there, a white tourist with a credit card in hand, and to see how the locals felt about the way foreign money was impacting their society.

All or nothing means that we have to chose between excluding outsiders entirely, or treating them as equals. A rich outsider shouldn't be able to use a pile of money that the locals don't have a say in and act like a king, but on the other hand there should be a gradual path to gaining the trust of the locals which has to do with whether you're helping or harming them.

I'll have to think about Nash equilibria. As for making the system harder to use... I guess there will always be the problem of displaying different prices to different people based on how trusted there are, but I think it's a small price to pay compared with avoiding the exploitation that rich foreigners visit upon poor nations: exploitation mediated by the fungibility of money. As for the other complexities of use, that's just software implementation details.