Similarly, AC also freely touts special fares ex-USA for asia which are cheaper than ex-Canada even though flights have to go through Canada to the USA.

These fares are specifically for the US market ... and these consolidator fares (sold through a travel agent) specifies that the purchaser must produce a US passport in order for the fare to be valid. You may buy published fares anytime but fares are slightly more that these 'specials'. They are not 'race' specific though.