Drive north on the 101 from Palo Alto toward the San Francisco airport, in a car equipped with the most sophisticated self-driving hardware available today, and two things are sure to happen. First, at least one other driver will look over in shock as the car pilots itself for long stretches at a time.
Next, as the time-worn lane stripes fade, as the concrete gets very light in color, the car will fire off warning lights and sounds as it drifts into another car's lane. It can't read the road. It can't yet truly drive itself.