They probably don't do much but as with your province, they are required in my state. They are probably required in all of the US under the uniform vehicle code. Colorado law states that a bicycle must have a white light in front, reflectors capable of being seen at 500 feet on the wheels and a red rear reflector. Although I think that active lighting is far better than passive lighting, i.e. reflectors, I still run them. I don't want some lawyer getting his client off by claiming that I wasn't in compliance with the law and therefore responsible for my own injuries.