I do question how desirable Canada truly is as a destination. However with regard to family sponsorship from other developed countries, fraud is generally non-existent. Purely out of my own experience, Europe, Australia, and the USA are more highly desirable for immigrants (non-family sponsorship). Social services are far superior in Western Europe (also you can live anywhere in the EU), the USA has more broad employment opportunities, and Australia is comparable to Canada and also has the added benefit of being able to live and work in the New Zealand once you get citizenship. Remember Canada'a health care system is good but it still ranked 30th in the world, pretty middle of the road.
Also, there is no income requirement for US green card applicants, especially if both the sponsor and applicant are out of country. Generally the USA just wants to know you can take care of the spouse (which you can prove in multiple different ways). Unlike Canada, USA green card holder can access all social services. In Canada, new spousal PR holder can access things like welfare but their spouse has to compensate the government if this is accessed within the first 2 years of residency.
To get to the heart of it Canadian and American couples or families shouldn't have to make a life changing decision on what country to live in. It should almost be like deciding to move to another province. Both countries already have access to each other's citizen databases, the application process is virtually a redundancy now, and comes off as a money grab or 'make work' project for civil servants.