Very good questions, I think I have mentioned some reason why the research might fail, even when done actually. But I must admit that Canada does a much better marketing of promoting itself, better then the US for example, much better.
The problem is that almost all skilled immigrants have unrealistic exceptions before coming to Canada. And when they lend here and start looking for a job in their profession the truth unveils. First don't get excited by government statistics about unemployment rates, they should mean nothing to...