Most Canadian Physicians near the border (in my experience) have visiting privileges at nearby US Hospitals.

Any Canadian specialist who a US hospital wanted, would bring them in, and pay them in a consulting role until their paperwork came through. They work with licensed MDs', and as long as a licensed MD signs the treatment paper it is all good.

It especially works well, when the Canadian specialist works with MD's who are taking a residency in a specialty. The Canadian recommends the treatment, and the licensed MD executes.

Simple as that.

let ME tell YOU