I don't completely understand why the salary cap was there in the first place - basically if a doctor earns a certain amount of money (say $300,000) they would have to stop practicing for the rest of year because they couldn't earn more than their cap/year. Many doctors would reach their cap in ~6-8 months and then just wouldn't be able to work for the rest of the year.
My understanding of the Canadian heath system though is very slim and I'm not sure whether or not the cap has a major impact on why there is such a doctor shortage there? I think a lot of it has to do with their universal health care, which would explain why so few doctors are taking new patients, why so many ER's are on the brink of closing, and why waiting times for checkups/surgeries are astronomical.