If you are surrounded by people in orange vests, or traffic cones directing you to a detour, you are in a construction zone and better not be doing highway speeds. The fact that the sign wasnt visible, or even wasnt present, will not help. This comes up in AI cars all the time. The camera is blocked from seeing the sign beside the road, perhaps by a truck in the right lane. Or maybe the temporary folding sign is blown over. You still have to recognize a construction zone. A bad sign might get you out of a basic speeding ticket, maybe, but it wont protect you from a dangerous driving ticket, or going to jail after running over a construction worker. And a great many juridictions mandate vastly reduced speeds when cops/ambulances/firetrucks/towtrucks are beside the road, meaning you have to recognize such situations regardless of posted signs.
Well, sure. But in the context of enforcing a limit on a human - by either reporting a breach or actively preventing the car from exceeding the speed limit - and not the car driving itself, I don't see any of that being an issue.
