One Thing Humans are Still Better at than Machines: Turning Left
In the Boston Globe last week, Hiawatha Bray wrote a fascinating article detailing one of the toughest programming challenges for self-driving cars: teaching them to turn left safely. Left turns are challenging because they involve crossing lanes of oncoming traffic while interpreting psychology and predicting other humans' behavior. You have to know how to read the signals to determine when it is safe to make the left turn in many different conditions.
Driverless cars do not know how to read humans and anticipate what human drivers will do. Humans know as they enter an intersection to begin to look for clues about what the other human drivers are doing, or likely to do so we can turn safely. Self-driving cars aren't this smart (yet) as they cannot read body language. At some point, self-driving cars will begin to communicate with each other at intersections so they can safely turn left.
Source: https://apps.bostonglobe.com/business/graphics/2017/04/driverless/series/teaching-a-driverless-car-to-turn-left/.