1. We have a large homgoneous market where you can build a product and it’s expected it can succeed for hundreds of millions of Americans
2. EU is the easiest second market, and another step change of hundreds of millions of customers in a somewhat unified market
3. there’s not an easy 3rd economy that replaces EUs wealth, population, and comfort with English + technology
When we piss everyone off in the EU tech company growth gets kneecapped and limited to US / Canada. Theres not an easy market to expand to without much deeper focus on that specific market and its needs, for much fewer returns.
Canada is very much in the same boat as the EU.
In addition to that, since we're on the car angle, Chinese EVs are basically just privacy nightmares. I mean, all cars are at this point, but that's why we definitely don't want Chinese ones coming across the Canadian border and ending up all over the place.
In the end there are in fact legitimate national security concerns that the tariffs address and Canada risks weakening those. So, that is the actual answer to why.