It's one thing to ramble on (like we do) about how autonomous cars are way safer than human driven cars, but it's another thing to prove it. Like, mathematically. A research group at Carnegie Mellon has created a distributed control system for autonomous highway driving and then verified that it's safe. In other words, the software itself provably cannot cause an accident.
To do this, the CMU group started with a simulation of just two cars (equipped with sensors and short range inter-vehicle communications) in a lane, and then proved that their software kept those cars from having an accident 100 percent of the time. With this as a base, they slowly expanded the simulation, adding more and more layers like multiple cars and lane changes until they had an entire complex autonomous control system, each module of which is definitely safe.
Read the full history on IEEE Spectrum Automaton blog