Originally Posted by
Steve M
Because they have no way of verifying the passenger's address. Nothing gets sent or delivered to the passenger's address, so there's no feedback loop. If it were as simple as a Canadian wanting to avoid Canadian tax on airline tickets while using their Canadian credit card, and all they needed to do was to put in US address in their profile, then everyone would be doing it.
That is all that is needed. If the address for the card is not in Canada, then AA will not issue the ticket in Canada but in the USA and so charge taxes applicable for ticket issued in USA
If someone holds a Canadian credit card but has address in US for example, then it will automatically use US issuance - it is not checking the card number for country of issue ( although it could if it wanted )
Checking a few more countries for ticket issuance on ITA ( UK, Thailand, Germany, Australia ) - all seem to have the higher tax liability