* The parent comment didn't caveat "large airline".
* Porter is the third-largest airline in Canada. Canada has 10% of the population of the US, so our airlines will be accordingly smaller.
* American Airlines is the largest airline in North America [1], serves the entire country + international. Really not a reasonable comparison to a regional domestic airline.
[1] https://en.wikipedia.org/wiki/List_of_largest_airlines_in_No...
No, it speaks to the population of Canada... Porter still comes in at 18th largest in North America [1]
(It might also be because each of the two large carriers, Air Canada and WestJet, has a number of subsidiaries/wholly owned sub brands which would each be larger than Porter - eg Air Canada Rouge, WestJet Encore)
[1] https://en.wikipedia.org/wiki/List_of_largest_airlines_in_No...