There's a difference between looking at the speedo because you're rechecking your speed and feeling pressed into doing it out of fear of being caught speeding 2kph above the limit simply because there's variability. I'm not saying it's hard, I'm saying it's distracting and stressful having to constantly poll and check for an arbitrary number that bears no actual relation to safety (which is the factor that drives anyone's natural speed limit feedback loop). IOW here I'm talking about the psychological effect that induces fear, stress and guilt in the driver, not the technical ability to do it. I believe coercion is not the proper way to educate people into living respectfully together.