AC might have higher costs comparing to WS, HU and AM.
Secondly, PEK and MEX each have population that is much greater than YYC, implying greater shares of originating passengers, even adjusting for the lower wealth. This is important because local carriers enjoy greater advantage among sales from its home country, especially for high yield business travelers due to more sales channels, bulk contract or FFP considerations. Thus HU and AM can draw more high yield passengers from its hub comparing to AC from YYC, a much smaller city.
Also, AM can offer a good selection of onward connections throughout Latin America via MEX whereas AC has no interline partner with a hub there. Flying out of YVR, AM has much better connection times via MEX than the other major Latin American gateway - UA via IAH - which usually requires taking the 6:00am flight to IAH then having an all-day layover before evening departures to South America.