The comment that people on average generally make more in US cities is completely false .
It certainly used to be true before 2007 and several decades leading up to it. Having up to a 25% unemployment rate brings down the US per-capita averages by a lot. USA ferility rate is also much higher than Canada's now (2 kids per female versus 1.5) which can throw out the numbers if not restricted to working age.
At this time Canada's per-capita income level is higher than the United States as is the Canadian per-capita GDP; it stands to reason that Canadian cities would be doing comparatively well over US cities.
Of course, I also expect this to revert again over the next decade once the US starts firing on all cylindars again.