But a lot fewer would be doing this.
There is a problem: securing the Mexican border will take a lot of money. The only likely way to justify the expense would be to justify it as security against terrorists infiltrating the U.S.
The problem: the terrorists are most likely to enter Canada as refugees, get Canadian citizenship and welfare benefits, and cross the border legally on a Canadian passport...
another way to justify it is that it will pay for itself by saving us money on detention facilities, health care, court proceedings, education, law enforcement, English classes, and all the other costs (financial and otherwise) that the illegals bring upon us