Self-driving has had too many "fake it til you make it" startups. Cruise started that way, and suckered GM into buying them for $1 billion. Uber bought Otto, and we now know how fake that technology was. Tesla hyped their basic lane-keeper and car detector into an "autopilot" then repeatedly plowed into clearly visible obstacles and killed people.
(Despite all the blithering about edge cases, they haven't been big problems in practice. The serious Uber and Tesla accidents were not edge cases. They were blatantly obvious obstacles: a semitrailer, a fire truck, a fixed barrier, and an isolated pedestrian on an open road.)
Waymo, meanwhile, keeps plugging away, driving around, getting their level of disconnects down each year, improving their sensors, and doing large scale tests. Once in a while they get rear-ended. If they don't get killed by Google/Alphabet's attention deficit disorder problem, as happened to Google's robotics efforts, they're going to get this into production.
It's not easy, and it's not impossible. It's just hard, like television or xerography. Those took decades from first demo until they worked well. This doesn't fit well with the startup make-money-fast model. It does fit with the big-company R&D lab model.
[1] https://techcrunch.com/2019/01/29/argo-ai-acquires-permit-to...