Except that in the case of Canada, there was a great deal of trade in both directions, in terms of commodities and also finished goods. It was a mutually beneficial trade arrangement too. It promoted the US' interests without ham-fisted authoritarian threats. This sort of trade made the US the powerhouse it was. In other words this was a sharp shift in US government attitude from one of friendship to one of an adversary (which is really how all relationships and business deals have ever been done in Trump's life). Sadly there's no going back. The damage is done and the US will never ever recover the good will and trade benefits it once had with its closest allies and trading partners, no matter what a future Democrat does to try to undo the damage, now that Trump's attitude has become the attitude of the GOP.
With China, though, there was no abrupt shift. China's goals have always been clear. The only thing they want from the west in terms of trade is raw commodities and foreign currencies. Whereas the west demands cheap goods, full stop. So China's domination of European industry and economies has been ongoing for years, and it's benefited by European policy and attitudes. China is happy to build high quality items and sell them for a premium, but there's no very little demand from the west. If there was demand, we wouldn't have seen local manufacturing capability disappear in the first place. Tariffs are not going to change these fact.