But like I said, your typical business traveller will not go through such inconvenience
There was a time when I might have believed that. I always thought that I was special, the exception, the one who would try things others wouldn't. But of late, with pretty much all of the other travellers in my company as well as so many others, it's becoming more clear every day that many, many business travellers will happily incur some "inconvenience" if the payoff is big enough. And these days, it doesn't take much for a "pay off."
you would need a significant number of leisure travellers to do this before such an impact is felt on the bottom line of Canada's air carriers. In other words, not enough people do it. Sure, some do. But not enough. That's the point I'm making. For years everyone has known that BUF and SEA are cheaper to fly out of. Well, if price trumped absolutely everything, then why do YYZ and YVR still have people flying in and out of them?
The question is not whether a small US airport can put a large international Canadian airport out of business. It's a) can they attract enought business to be successful, and b) will they have any impact on fare/airport fees/etc in Canada?
I don't know, but I suspect that it at least helps keep the Canadian airports "honest." Given the example of BLI (and in fact all of Bellingham, which probably circulates more CAD currency than USD) it
can be done.
But your various arguments seem to amount to there might be some tiny impediment which reduces the perceived savings ever so little or there may be some minor inconvenience. They might not know about Nexus. They might have to take a ferry. They might have to drive for more than a single hour. There might be a Shriner on a tiny motorcycle in front of them.
They're not very compelling arguments.