Earlier quoted context omitted.
Amex and Discover are different as those are closed-network. I think it's really hard to argue Visa/MC is not a duopoly. Unfortunately anti-trust enforcement in the US has been more political than anything.
I would say this is an example where a duopoly is useful for consumers. The duopoly allows consumers the ability to use a credit card pretty much anywhere they want in the US; This is pretty convenient if you use a credit card responsively. It is also a better solution than the old days where you would have store cards or a store account. (I am not saying the duopoly is great because these companies are a massive hea…
Going by that reasoning a monopoly would be even better, as the card would be accepted everywhere.
The consumer pays by lack of innovation and high scheme fees.