As a point of clarification to my first post , #6 in this thread, I took the descriptions of taxes and fees from a hypothetical ticket YUL-MIA-YUL as shown by ITA software. Whether YUL's CDN15 is a tax or not doesn't change the demand for its payment. Ken pointed out that U.S. equivalents 'PFCs' are capped at a much lower rate. This was the language I used, new emphasis added.
For Montreal travelers with a US destination, this would avoid a lot of the cross-border and YUL airport fees. Please forgive the co-mingled currencies.
Tax: Canadian Air Travelers Security Charge C$7.94
Tax: US International Arrival Tax $15.10
Tax: Quebec Sales Tax C$1.19
Tax: Canadian Goods and Services Tax C$1.38
Tax: Montreal Airport Improvement Fee C$15.00
Tax: US Immigration Fee $7.00
Tax: USDA APHIS Fee $5.00
Tax: US International Departure Tax $15.10
total $42.20
Further, I had deleted two lines of Canadian GST as I don't know if this would be payable on purchases in Canada for tickets U.S. to U.S., as with a hypothetical Plattsburgh-Miami.
Tax: Canadian Goods and Services Tax C$15.99
Tax: Canadian Goods and Services Tax C$7.35
These amounts may not correlate to the fare basis used in the example a few days ago.
The point was to show that savings from avoiding both Canadian and U.S. taxes and fees for cross-border air traffic are non-trivial. This is particularly true for larger traveling parties. How Montrealers view the value of their time and preference for U.S. land border crossings vs. interrogation at YUL I can't quantify.