It is because of the British parliamentary system. What happens is a vote "first passed the post". This meant that the popular vote when tabulated, gave these figures.
Liberals 39 percent.
Conservatives 31.8 percent.
NDP (socialist) 22 percent.
Others 9 percent.
In the previous election the Conservatives got the 39 percent and the Liberals the 31.8 percent. A Conservative majority. It is said by the pollsters that vital 8.1 percent changed the course of the election. Thus 60 percent of Canadians did not vote Trudeau's Liberals. The party poo bahs pick their leader, not the public. Unlike the US system where it is head to head for the individuals seeking the presidency.
If Trudeau screws up big time the Liberal Party will dump him and find New Leader(PM) ,unless they’re all as Crazy as Trudeau is