Speaking for the Mexican workers, I know for a fact that the Mexican consulate only recruits married workers to come to Canada, because it's a guarantee that they will go back.
That said, do they want to stay in Canada? If they can bring their family into Canada, I think you would probably increase the pool of workers who may want to come in. Both live-in caregivers and agricultural workers are denied any type of family reunification. They can't come into Canada, only the worker.
Some Mexican workers I have spoken to have come here and they don't like it. So they work here for their contract, they go back, and they don't come back next year.