What I've never understood is how you're going to get a car to understand a construction worker or cop doing hand signals without artificial general intelligence. Why even bother with the car until you've figured that out in the lab?
If the worker indicates you to go into the opposing lane, how long should the car remain there? How do you tell the construction part is done and you should return to normal self-driving logic? Sometimes there are cones, but sometimes not. American workers do often have Slow / Stop signs, giving a clear indication of when to move at least.
If you are going down a street slowly, and someone is wearing a hi-vis vest for their own safety, and they point at something, is your car going to follow that pedestrian's instructions?
I actually found that looking for a years old article about Google's system accounting for bicyclists making hand signals, but there you go.