This is a populism move, not pay-to-play. The imminent reality would have been this: many Americans will want to take a vacation to Canada to get a deal on their phone. That just doesn’t make sense.
This being favored by the decision
If they’re following the law they’d have to declare the purchase when they come home.
And then they can ask you for your Form 4457 that you filled out and presented to CBP before you left the country. Don't know what that is? Oops. Full duties owed on that iPhone then, thanks.