WASHINGTON—U.S. President Joe Biden appeared in no mood for compromises Thursday as he welcomed Prime Minister Justin Trudeau to the Oval Office, where the U.S. president offered the usual bilateral pleasantries but no hints he’s willing to budge on a controversial tax credit for American−made electric vehicles. Trudeau and Biden each sang one another’s praises before a phalanx of U.S. and Canadian reporters and cameras, a show of unity and continental solidarity before a three−way meeting with Mexican President Andrés Manuel López Obrador. But when the customary shouted questions turned to the subject of the $12,500 zero−emissions vehicles tax credit—a proposed measure the Canadian auto industry has described as a potential body blow—Biden showed no latitude. “We’re going to talk about that to some extent,” he said. “We haven’t even passed it yet in the House … there’s a lot of complicating factors.” It’s too early to assume—and highly unlikely …