I think Ian Malcolm, the chaos theoretician in Jurassic Park gave the best (in the novel) explanation as to why we can't outsmart the universe. Mathematically, chaos wins. Life/Chaos beats the best-laid plans of mice and men. Humans are best at all-purpose threat response in unusual situations. The sheer audacity of the belief that we can build a billion two-ton computers and let them loose is staggering.
I stand watching a computer-dispatched elevator sit on a floor, opening and closing its doors, and no one can make it stop. They have to call Otis every time. And it happens a lot. That's a damned simple sensor and interface, and it fails. No one pays much attention because there are five other elevators. If the elevators were doing seventy among hundreds of other elevators, it would be more tragic.
A car would consist of two or more networks, dozens of sensors, hundreds of millions of lines of code that absolutely must work, and would work best if all the other cars were running the same code and are integrated into a worldwide network. This assumes the sensors don't fail eventually, or that the owner doesn't, and this might shock some Americans, trade in their car every two years, but instead keep their cars for a decade or more. They do that because new cars last that long, easily. A robot car would fail in hundreds of ways in that ten years, because of normal failure of all that incredibly delicate self-driving equipment. I guess everyone HAS to buy new every few years, as the manufacturers really, really would like it if they do, so I assume code updates won't be all that forthcoming on older models. Bricked or new, your choice. Cha-ching. No wonder they're so very, very happy to build robot cars. It's a license to drain all the damned wallets.
And of course, we can't ignore that car AIs with outside network connectivity are, by definition, remote-control ready. If anyone thinks this isn't a power dream, really? Recall also that America isn't the only country in the world. Remote monitoring and override of cars will be used by secret police and evil bastards in nearly every nation on the planet to nail journalists and malcontents. Damn, this is gonna be a well-behaved world when they are done.