And they wouldn't have been too far off! Waymo became L4 self-driving in 2021, and has been transporting people in the SF Bay Area without human supervision ever since. There are still barriers — cost, policies, trust — but the technology certainly is here.
So it's not as ubiquitous as the most optimistic estimates suggested. We're still at a stage where the tech is sufficiently advanced that seeing them replace a large proportion of human taxi services now seems likely to have been reduced to a scaling / rollout problem rather than primarily a technology problem, and that's a gigantic leap.
That's where we are at with self driving. It can only operate in one small area, you can't own one.
We're not even close to where we are with 3d printers today or the microwave in the 50s.