The economy is large enough in the US that there are plenty of opportunities. The entire economy of Canada is roughly the size of Florida, yet has 2x the population.
If you can't find a job or opportunity in Orlando or Tampa, you can always move to Atlanta or Dallas or NYC or Charlotte or Sacramento. Within Canada you don't have a similar option - most jobs are located in a handful of highly expensive cities (Toronto, Vancouver, Ottawa, Montreal, Calgary), which limits your mobility.
There is no city in Canada that has both relatively high wages and relatively low CoL. There is no equivalent of Phoenix or Columbus or Dallas within Canada.
Additionally and separately, what you are saying about high paying jobs in a select few cities is true here also. I worked for a company based out of Atlanta and got paid like crap . There isn’t really a lot of tech jobs in the tier 2 cities you are bringing up.