It had all the trappings of an announcement both noble and innocuous. To help postsecondary students unable to find summer jobs during Canada’s coronavirus outbreak, Prime Minister Justin Trudeau unveiled a $670 million program to provide grants to those who volunteered in their communities. Now the Liberal party leader, who once promised unprecedented transparency in government, faces accusations of cronyism and self-dealing, his third ethics probe as prime minister and the revival of long-standing questions about his judgment. Trudeau apologized this week for failing to recuse himself from the cabinet discussions that led his government to tap WE Charity to...