You can have all the sensor-tech in the world, but self-driving cars aren't going to take off until you have standardized car-to-car communications and smart roadways designed for self-driving cars, such as pre-mapped lanes and surfaces as well as smart roads communicating road-condition and obstruction information.
Car-to-car communications are not necessary for automatic driving. They may even be undesirable, as a potential source of bad info. Google/Waymo doesn't need them. They make the point that there are lots of things in the environment, from bicyclists to moose, that aren't going to cooperate with the system.
The need for super-detailed maps is probably temporary. A reasonable goal is to have the ability to drive anything with a basic map (Google StreetView level) at slow speed, then retain info to do it again at faster speed. Some of that mapping info may later be uploaded for use by others.
I really hope they get self driving cars working with nothing more than current GPS maps, plus lots of sensors. Considering the drive I took this weekend, past actively changing construction zones, landslides, along infrequently traveled roads (and even a logging road), I wouldn't want to trust my life to stale data.
We did all that in the DARPA Grand Challenge over a decade ago. Most of the problems today involve dealing with other road users.
(Some of the self-driving car projects today are less capable on bad roads than the off-road systems of 2005. They don't have to be; it just comes from focusing on lane following on freeways as the primary goal.)
I'd love to see self-riding multileg robots, like an advanced version of Boston Dynamics alpha dog. You don't even need roads for them. With some kind of super-stability they could become more comfortable than vehicles. Perhaps we'll have human carying drones a bit soner, though. Still, in a bit more distant future, roads might become obsolete.
Riding one of those, galloping along at 70mph, would be quite something. (I guess it's the legged-equivalent of a motorbike?) You'd have to have a lot of trust..
We do car-to-car communications already via signaling. Bad actors also exist right now and are handled via regulations. The same will happen under autonomous systems.
The final check will be sensors, but the system relies on cooperation.
A "digital rail" with centralized traffic control is much safer and much more practical.
Autonomous is a dead end. People make the mistake of looking at early progress (starting at 0 base line) and thinking it will not stop till it is perfect.
It is like when we went from 100mhz to 1Ghz chips and people were saying "in 10 years we will have 10Ghz chips" but in reality we never will.
Sure, but that means separated roads without pedestrians, cyclists and non-autonomous vehicles. Not really politically possible. And it's an incompatible system, so you don't have any benefits until you've sunk a huge ton of money - a total non-starter in most countries.
