The page on YVR SS access does not mention South America because there is no direct AC flight from YVR to South America. As others have pointed out, you cannot physically get access to YVR SS on a connecting domestic flight.
If there is a AC flight from YVR to South America in the future, I believe it will be eligible for YVR SS.
For the same reason, YYZ SS access page does not mention Australia or New Zealand, but a hypothetic YYZ to SYD flight will certainly be eligible for YYZ SS.
Originally Posted by
mahasamatman
They are connected airside. We have used the international MLL before a domestic flight in the past.
But I do see now that the rules exclude South America, so that puts an end to that idea.