I think you misunderstand the comment about exchange rate.
In Canada, the price difference of goods with the U.S. is beyond just the exchange rate.
Thus, you can convert a salary between USD and CAD, but that doesn't account for higher prices of goods in Canada (beyond exchange rate differences).
This is why many Canadians shop in the U.S. (if feasible), or travel to the U.S. to make big purchases (such as cars).
When CAD gets stronger, w.r.t. USD, prices in Canada don't respond proportionately.
Likewise, when CAD gets weaker, prices in Canada tend to respond quite rapidly.
It seems asymmetric, and is another factor when comparing US/Canada cost of living.
I'd love for an economist to explain this. It's never really made sense to me, but anecdotally, it's well known phenomenon in Canada.