There a plenty of places where it's safe for a human to drive much faster than the speed limit. There are places where it's neither safe nor reasonable to drive under the speed limit, because no one else does and you're likely to get rear-ended. There's a red light near an intersection where I live that's pressure sensitive and not quite sensitive enough to trigger when a small car is the only one waiting; at 3 in the morning when the roads are empty, it's safe and reasonable to check that no one is coming and then run the light rather than taking an alternate route because it'll never change. We mostly have to hope the police are reasonable when the laws aren't now. I doubt self-driving cars will change that, certainly not until all or most drivers have them.