Cars going through red light repeatedly

I use the pedestrian crossing by the library (on Calder St) regularly and many times I have seen cars going through a red light here (when it's green for pedestrians) - I don't know if there's something about the lights that drivers can't see them clearly? Or if cars are going too fast to notice the lights? Either way, having to check if a car is coming before crossing, even when the person is lit up green, renders the traffic lights pointless and actually unsafe as many people rightly assume it's safe to cross with the green man lit up!