This is from my personal experience and from having talked to a few people.
I moved to Toronto about 5 years ago. I have a Comp Sci background and had worked in a top US ecommerce company. After a couple of weeks of search and a week of interviews I had 4 offers but all of those from Canadian subs of US companies. No Canadian company even contacted my after I had applied, not in those weeks of my search nor in the interview week nor afterwards. I had relevant experience as advertised in the job reqs. so lack of fit can be ruled out.
My wife, who is a statistician, had a horrible time. She had worked in US for major pharma companies for about 5 years, studied in US for 5 years prior to that and has quite good communication skills. She wasn't entertained because she didn't have enough "Canadian experience" whatever that means as distinct from "American experience". I've heard this lack of "Canadian experience" often being a barrier.
After all these years I am still puzzled how a Canadian experience is distinct from an American experience especially for individual contributor (and non customer facing) roles.