Bluster is great, but alone it can't overcome the fundamental technical challenges of a self-driving car. And those are many! Cars have to talk to one another, or at least know where other cars are. Besides other vehicles, it's important for cars to understand other objects near the road, both static ones like fire hydrants or movings ones like people. It's huge, and Google, which is in many ways in the lead on this technology, is still testing cars in both a virtual world and the real one.