Originally Posted by
callum9999
And £28 is correct (AA quote £29). Canada has high airport charges and the US has high international arrival charges. I can't imagine YVR-SEA has ever been $6 (in recent history anyway) - you're presumably thinking of SEA-YVR, which avoids both the Canadian airport fees and the US international arrivals taxes.
This is correct.
Many Canadians drive across the border to BLI or down to SEA precisely to avoid these taxes and to access cheaper US domestic fares.