To be fair, there are problems with speed cameras that we've seen in the US, so probably similar problems exist in Canada. For example, they're often outsourced to private companies, and there are privacy and accuracy concerns. Local governments with access to speed cameras can make a lot of money from speed traps, and so they have a financial incentive to make the road harder to drive on, when they should be making roads easier to drive on. People sometimes see speed cameras and slam their brakes, which can cause all sorts of problems.
Usually, the better way to control speed is to design your roads to naturally be a certain speed. Some ways you can do this is by controlling the width of the lanes, the length of the lines in the lane dividers, and the curve of the road.