If taxpayer dollars are going towards an individual who covers his or her face, the insinuation is that person is hiding something. It is fair that someone's face must remain uncovered because of government accountability--Quebec can't give out assistance to some "faceless" person who seems to be concealing their identity.
Issues of terrorism an religious beliefs aside, it is simply to easy to defraud the government when one's true identity can be masked. Identification papers can be easily forged. It isn't impossible to believe that males may don a burqa in order to claim a need for child assistance and recieve thousands of dollars a year in government food or cash subsidies. it is the governments right to know they are giving benefits to the person claiming them. While it wouldn't eliminate all fraud, it will allow for one of the most basic forms of identification; facial recognition.