You have missed the point behind the American employee they needed to use as your replacement.
None of what you experienced has anything to do with wages, first of all.
What this has to do with is the fact that you work for an American company that has one of it's business operations located in Canada. Before you quit your job, you were a Canadian living in Canada but working for an American-owned company. Let's be clear, that's where you're coming from here.
All American companies have a mandate from Trump to hire only American Nationals, not imported immigrants even inside the borders of the USA. That is America's new direction in it's evolution as a developing Nation, to turn inward and become an isolationist, protectionist country unto ITSELF.
When Trump first came into power as President back in 2016, one of the first things he mandated was a return of corporate America BACK to the United States to secure American jobs at the expense of the workers laid off in whatever country those American companies pulled out from, at Trump's Authoritarian command.
Where this first hit Canada was in Leamington Ontario, about a 30 minute drive from the Windsor/Detroit border crossing on the north shore of Lake Erie.
Heinz who make ketchup, are an American-owned company with it's Head Office in the USA. Heinz had been in business in Ontario Canada for over 80 years making ketchup and mustard and relish using Canadian-grown vegetables and using Canadian employees, most who'd been employed by Heinz for over 40 years as of 2016.
When Heinz pulled out of Canada in response to America's new King thrashing his golden gauntlet against his oval office oak desk, Heinz laid off every Canadian employee, walked away from the factory that was built 80 years ago with Canadian government funds, then set up shop right across the lake on the American side where Heinz then hired Americans to do the same factory jobs Canadians had been doing for the previous 80 years in Canada, but were working on behalf of American-owned Heinz.
Stellantis Automotive who make the American-owned Chrysler who make the Jeep and Ram Truck, had a production factory in Canada which recently closed for alleged retooling, who then laid off all Canadian assembly line workers during the transition, but recently announced that the Jeep and Ram Truck would now be manufactured south of the border, somewhere in the USA.
Stellantis is a Dutch-owned conglomerate who received orders from Grand Master Trump to either transfer those Canadian automotive jobs to the USA, or they wouldn't be able sell Jeeps and trucks in the US market. Stellantis pulled their Chrysler division out of Canada and returned those jobs to the USA on Trump's command and those Canadian employees are still unemployed.
To the heart of your post, the only reason that an American would be solicited to take your place after you quit your job was because the company you worked for would be under the same mandate to use AMERICAN employees, not Canadian employees.
The problem is, Americans are not exactly welcome in Canada right now and no American in his right mind would actually pull up stakes and move to Canada even in good weather, which is why they had to offer your replacement more than double the wages you were making as your replacement.