I guess you never really know how expensive cancer treatment, for example, can be since you will never see the medical bill. While the number of cases are low, the cost of such treatment is still high enough to make an impact on overall cost. If medical cost in US can cost someone's mortgage, I can only imagine that it can have an overall impact on medical cost in Canada.
You talk about how Canada need immigrants to support the social net in Canada. What's the point of bringing over immigrants if they are only staying long enough to obtain citizenship and leave. Their action won't help Canada in the first place.
I wanted to add here something.
The numbers of cancer cases are on rise in Canada (not low as you think). You may get surprised to know that almost 1 in every 2 Canadian will be diagnosed with cancer, according to Cancer Society of Canada.
I doubt that people without having any family back in Canada may move here after being diagnosed with cancer only for the treatment from where they are already settled. There is not a one shot vaccine for cancer, but a long and complicated process where the patient needs someone taking care during that long process. A lot of emotional aspects are also associated, including family or friends back home among others. That means just buying a one way ticket is not the case but several factors are to be considered. It’s needless to say that countries like India are already capable of treating many diseases at reasonable costs. Cost of chemotherapy is more affordable in India and other third world countries than in Canada, but you may argue about the standard of the care in cheaper hospitals there. But people have recovered there as well, and not everyone in Canada or even in the US gets the level of the treatment provided by MD Anderson, Texas or Memorial Sloan, New York or Princess Margaret, Toronto. As
@ZingyDNA said, it’s worthless to discuss about the topic without any statistics.
If you ask my opinion, I don’t mind few hundred unfortunate people coming back to Canada looking for cancer treatment, I will be happy that my tax money is used in humanitarian causes. Don’t forget the money paid by the healthcare system remains inside the country, and every patient treated is a case study which helps to determine the direction and treatment plan of the disease in future cases as well as to develop the therapeutics. As myself being familiar with the research related to such diseases, I know that every patient treated contributes to discovery of the new medicine and development of effective therapeutic strategy in the future. There are other unfortunate cases where Canadian residents (with properties and job in Canada) happen to have an accident or heart attacks while being outside Canada and end up being treated there out of pocket, let alone a non-resident planning to come here for the treatment in a similar situation.
Of course everyone agrees Canada needs more immigrants not only to contribute to the social system but to make real estate giants, retailers, communication giants and so on more richer. And governments (present or past) know how important the mobility of a worker is, thats why they agreed for the provision of TN visa in NAFTA agreement!