A smart human can learn to drive safely in, say, 50 hours. Self-driving cars, in theory, can think and react more quickly than any human, and prototypes have logged millions of hours and tens of millions of kilometres.
So why are they still getting things wrong? Few people have thought as deeply about the subject as Dr Gill Pratt, robotics and AI expert, former MIT professor, and now head of the Toyota Research Institute (TRI).