Does anyone actually believe these companies at this point? Who actually aren't saying much any longer.
I'd be far less surprised if Google shutdown Waymo in a year or two than if they actually introduced a door-to-door driving service in an urban area without a safety driver present.
And technology is accelerating at a much faster rate today.
I'm sure a lot of people believed that in 1970 but look where we are now. Technology accelerates at a much faster pace but often times in ways that you don't expect. The people in 1970 probably didn't imagine smartphones with a global 4G network but instead of flying cars we got this.
Deep learning/machine learning have made remarkable advances in recent years--primarily because of both computational (esp. GPU) and storage/data advances.
However, in spite of a lot of money and talent expended on understanding organic brains and human-level cognition over the decades, progress has been slow and there's a general belief among scientists who work in AI spanning CS and neuroscience that there are aspects to human learning and reasoning that we just don't really understand yet.
And that more deep learning, data, and programmed rules won't get you to autonomous vehicles outside of some limited domains. (Which is valuable by itself; it just doesn't get you to robo-taxies.)
I actually do think highway driving can be automated relatively easily but that still assumes a competent licensed driver behind the wheel.