I can't find it now, but about 5-10 years ago I saw a talk on youtube where a guy suggested that we should demonstrate to the public how safe driverless cars are by having volunteers run out in front of them on a closed stretch of road... As if the laws of inertia and friction don't apply to driverless cars.
Around the same time I watched an information video published by the Swedish road authority where they claimed that they will be able to make roads in Sweden a third narrower once all cars are driverless. I guess that would work, were it not for winter and rain, and again those pesky laws of inertia and friction.
The thing that I think a lot of people overlook is that human drivers are actually pretty good at not getting killed or seriously injured while driving. Look at the statistics. Look at vehicle between deaths and vehicle miles between serious injuries in the US. It's not going to be easy to build driverless cars that can match those numbers. I highly doubt that Google or Tesla is anywhere near that level of safety.
I don't doubt that driverless cars will become an order of magnitude safer than manual cars unless they get banned (or effectively banned through draconian regulation), but it's going to take many years to get to that level. In the meantime a lot of people will die. Some of them will die in accidents that a human driver could easily have avoided. I think it's going to be tempting for politicians to step in and demand extreme regulation.