Canada's market is 10% of the USA. Of course there's going to be an imbalance in trade. Trump doesn't understand this, and he thinks that it means that Canada (the government) is literally ripping off the USA.
Just like he doesn't understand that tariffs are paid by the buyer, not the government of the seller.
Finally, the current trade treaty between Canada-USA-Mexico was negotiated by Trump himself, and it replaced NAFTA. When he says it's a bad deal, why is nobody pointing out that he negotiated it? And famously said it was the best trade deal in history.
Republicans have an amazing ability to just ignore criticism. Their base is primed to also ignore any criticism. This makes it seem like everyone is bringing up a "non issue". It's wild. Thats part of why some issues seem to never gain any traction.
This is a major reason trump kicked a bunch of reporters out of the press pool. They challenged the narrative which doesn't let them ignore criticism.
My take is that part of this is the fact that the US far right took an interest in Canada after the "trucker" convoy protest here during COVID. Multiple Fox segments on what a terrible "communist" place Canada is. And so it's become a brainworm in Trump's head, among a bunch of others. And a useful demagogic point to distract or rile up his base with.
(Nevermind that DHS would have shot some of those protesters on site if the same kind of protests had occurred on the US side of the border. There's a reason the convoy was mobilized towards Ottawa and not to Washington, even though the vaccine requirements for truckers were actually a Biden regime initiative.)
That and a generally liberal government holding power directly on your border, in the same linguistic/cultural/economic mileux has potential domestic consequences / threat.
Just like he doesn't understand that tariffs are paid by the buyer, not the government of the seller.
Finally, the current trade treaty between Canada-USA-Mexico was negotiated by Trump himself, and it replaced NAFTA. When he says it's a bad deal, why is nobody pointing out that he negotiated it? And famously said it was the best trade deal in history.