Originally Posted by
cmd320
It wouldn’t be legal to transfer in Canada on a regular basis going from the CONUS to Alaska. That would be cabotage.
I’m not sure who allowed them in under the guise that it was a transfer to another domestic destination.
It isn't an airline transfer, they are driving from the lower 48 through Canada to Alaska. Or at least that's what the tell the border officials. Evidently there is/was some sort of agreement between the US and Canada to allow Americans to travel through Canada to access Alaska (or the reverse).
The link clearly describes the process.