>Where cash is stigmatized? I haven't seen such a place except PRC.
I don't know about stigma, per se, but there are a few places where businesses have a pretty explicit legal right to refuse cash, UK, Netherlands, Sweden, US. Oddly in PRC refusing cash is illegal.
Because "cash" isn't actually real, it's entirely a form of completion of a contract. The same contract that you could agree to complete by trading chickens, or bottles of bath water.