Some freeways have fixed point to point cameras 5km apart so you can't beat them by slowing down for the camera as they will get your average speed between the two points - same deal - 3 km over, fine. Cops will pull you over in their vehicles if they detect you speeding anything over about 4kmh over the speed limit. In Australia speed fining is all about blatant government revenue raising - this despite government propaganda calling them safety cameras.