The instant payment system run by Brazil's central bank is used down to the smallest transactions, including buying coconut juice from a street vendor. By settling account-to-account transfers in real time at no or low cost, it has become a way around card fee structures.

The American objection is whether it is fair for a government-operated network to compete with private providers. Brazil emphasises the public aims of financial inclusion and lower payment costs.

The argument touches public instant-payment infrastructure everywhere. India's unified payments interface, China's mobile payment ecosystem and Korea's account-based transfers differ in design but share a direction: less dependence on card networks.

Payment fees are a felt cost for Chinese-run businesses in Korea too. Which network becomes the standard shapes both merchant costs and consumer convenience. Hwagyo Sibo does not rule on which country's argument is correct.