No Google engineer taught the car that a bunch of kids on a field trip would march out in front of it at an intersection. It stopped and waited for them on its own. And no-one told it that, right after that, another car would run the four-way stop sign right in front of it. It handled that, too, avoiding a collision all on its own.
At first, those interactions seemed boringly normal to me until I remembered… no-one was driving! The car had done that all itself while the man in the drivers seat sat passively watching.