The World Trade Organization is the referee for 164 trading partners, each with their own political and economic agendas. Lately, those agendas have gotten more complicated — especially with President Trump’s tariff blitz. Roberto Azevêdo, head of the W.T.O., tells us why it’s so hard to balance protectionism and globalism; what’s really behind the loss of jobs; and what he’d say to Trump (if he ever gets the chance).