The auto industry is a shockingly high percentage of the Canadian economy, somewhere around 10% of GDP. Direct auto manufacturing roles are themselves about 1% of jobs nationally. If we start counting everyone involved with the sector, it's >5% of people in Ontario. It's not a winning political move to make all of those people unemployed.
Let's be real, if Trump wants to reshore US auto factories from Ontario to Detroit, as he has stated explicitly, Canadian politicians can't do shit, USMCA be paper after all. Right now CAN just waiting for term to blow over and hope there's no Trump3. But ultimately if CA auto is going away / shrinking to irrelevance, at some point winning political move is to give masses cheap cars.
Fair for Canada. In the US, the entire auto production economy employs fewer people than Amazon does in the US.