LAST MONTH Jamieson Greer, America’s top trade official, complained that Pix, a Brazilian instant-payments system, unfairly disadvantages American firms such as Visa and Mastercard. America proposed an additional 25% tariff on Brazil in response. Yet Brazilians seem unmoved. “Pix is a Brazilian achievement and we will not give it up,” replied Luiz Inácio Lula da Silva, Brazil’s president and a frequent critic of American power. Even his right-wing rival, Flavio Bolsonaro, said he was unwilling t...