Many of them have been there for five years or more. The analysis you gave is the proverbial apples and oranges. Canadian citizens would have various debts, along with cell phone bills, cable or satellite bills, hydro bills, credit card bills car payments etc.. If you were one of the Haitians walking across the border, the only conceivable bill they might have is a cell phone bill , as they all seem to have one. Any bills they might have had in the States would be in limbo perhaps never to be paid as they have no address, and probably no one knows for sure where they have gone.  Walking across the border might be the best thing that ever happened to them.