I was watching this video of a live chicken trapped on a moving truck and thought it was strange that it’s not possible to say anything to them even when circumstances might warrant it. All we got is honking and waving. There could be a touchscreen interface with a map of nearby vehicles. It could be voice controllable or the passenger could do it for safety.
I once had someone flip me off because I put my turn signal on. We were in the right lane, I was turning right, and the left lane was completely empty.