This is actually a really complex issue, it's not just a matter of government will or changing a law or two.

Medical school + internship can be a 7 to 10 year educational process. The process of vetting all of that education occurring in foreign nations to make sure it meets our medical standards can be a years-long project in itself, which requires some level of access and co-operation from the foreign nation. This obviously can't be done on a case by case basis. Canada has undertaken this successfully with some other countries... which is why (in BC anyways) we are blessed with a bunch of really great South African doctors.

One of the big hitches is this: no country wants its doctors going overseas. It takes a somewhat unique case, where a nation has an excess of doctors perhaps, and where govt and medical associations agree they should embark on standardizing their medical training with a foreign nation and start exporting some of their doctors.

On the Canadian side, the biggest impediment is likely our own medical associations. They are the ones finally responsible for accrediting foreign education, which you can imagine requires a lot of diligence, and we don't want them rushing this process. We might ask though, whether protectionism slows them down more. They are a professional association, and they don't want to open floodgates to foreign doctors who increase competition and make it harder for their members to have profitable businesses - which would discourage Canadians from entering the career and only further exacerbate our medical shortage.