I'll point out that there are two categories. One category is the parents and grandparents. Usually you have the parents, with maybe one parent who is inadmissible and the other who is not. In the economic category, often several people are contributing, with maybe one child who has an issue. That can be the impediment. Those are the cases that are really problematic from a practical point of view.
I want to clarify that I agree with Mr. Rae in terms of the moral issues involved, but I'm trying to appeal to your practical notion of what makes sense economically as well.