Before last week’s Republican convention, Donald Trump seemed to be moving away from the populism that characterized his 2016 campaign. “This time around, the former president isn’t even pretending to stand up to corporate power,” Rogé Karma observed in The Atlantic. “He’s defending big business, cozying up to billionaires, and wooing C.E.O.s.”When Mr. Trump named Senator JD Vance of Ohio as his running mate, though, pundits quickly concluded that he was doubling down on populism. Mr. Vance has been a leading critic of Reagan-Bush policy orthodoxy in the G.O.P., has expressed skepticism of further corporate tax cuts and has even...