Obviously stop signs, ramps and traffic lights are high on the list. But a note feature to report when something was incorrect or missing, like waze. For instance, someone stole the 65mph sign on this off highway, so autopilot limits speed to 40 when it's actually 65. And the graffiti covering signs.
On PCH going north in Huntington Beach, across from “dog beach” parking, before Seapoint Street is a 60 mph sign that had considerable vegetation obscuring the sign. I was amazed my 85 was able to see and record this speed limit accurately. About a month ago the vegetation was cut back. What’s interesting to me is that in another 100 yards is a 55 mph sign for trucks which does not register. For the missing/graffiti signs you mentioned maybe Tesla could use the autopilot improvement library it records, to identify these previous located signs. Or GPS. Problem, of course, is what if the missing sign is not an accident rather an actual change?
Google Maps
