Environment needs to be very simple for AI to cope
Autonomous trucks are being used on minesites in Oz, not for any happy progressive free-the-masses-from-having-to-think idealism, but for industrial/economic avoid-having-to-pay-and-feed-workers logistic reasons... and thus, operating for several years already.
These are controlled environments, limited in scope with barricades preventing random vehicles entering, and all authorised vehicles inside the zone communicating their positions and locations to central control, and road and engineering design and construction to make everything pleasing to our robot overlords.
And yet...
Crows had been swooping the trucks and triggering the collision avoidance detectors, and tumbleweeds ( the Australian equivalent) will set it off.
All this plus being vulnerable to network, software and hardware hiccups.