re: doctor shortages in Canada: When you maximize number of patients and maximize amount charged on a given procedure, it amounts to a pay cap. A direct result is that doctors go elsewhere. The regulatory system is also inefficient as you note in that those who are trained elsewhere encounter barriers here. Further, we don't empower nurses sufficiently instead of allowing patients to choose like in the US (Walmart / Walgreens). This says nothing about specialists who are even harder to find in Canada because incentives are even greater to move elsewhere (again a direct result of caps in the one payer system).
A related article from Macleans: http://www.thecanadianencyclopedia.com/index.cfm?PgNm=TCE... (also talks about the spending in attempt to integrate some of the foreign medical practitioners)
As to the shortage of doctors: Doctors in Canada are limited to the amount of patients they can see, not so much by what they can charge. (Although the rates for services are set, the same way they are often set by HMO's in the US.)
The whole reason this is done is to prevent doctor "factories" - doctors that spend 10 minutes with patients and provide poor diagnosis' in order to see as many people as possible.
The shortage is exactly due to the fact that they don't hire more. The number of semi-qualified medical professionals driving cabs in this country is outlandish. The doctoral societies have been not bent in their admission guidelines, and hospitals simply don't have enough space for all the people needed a Canadian residency requirement.
There are tons of people willing to practice in Canada.