You should have seen the floods of canadians in SEA (seatac) parking lots for spring break. It seemed like every other car in the lot. Everyone and their mother apparently would rather drive 3 hours from Vancouver BC than pay whatever taxes/extras/etc from flying out of YVR.
So does that argue for AS to match fares coming out of SEA, or for QX to start running service to CA or to LAS out of BLI, if the point is that people will drive down to keep from paying border fees?