You won't know if people have Level 3 "Self Driving" cars because unlike Level 4, the Level 3 cars always have a human sat in the driving seat, it's just that maybe the human isn't paying attention and maybe the car is driving anyway. It may be difficult to gauge (beyond guessing) how many people you see are bad drivers and how many aren't actually driving at all under L3...
L1 (the machine does some of the work but a human driver is always doing much of the driving) is certainly something you see and don't even think about. Intelligent Cruise control (ie it won't smack into the car ahead but instead slow down) on a motorway, maybe automatic lane keeping on somebody's fancier or newer car, it's not "Self driving" as you'd understand it, but it's something.
The way these "Levels" work is L3 to L4 is the point where we transition from "The human is legally driving but the machine is offering more and more assistance" to "The machine is legally driving and the human is asked less and less often to do anything at all". As a result a person who is literally blind and thus couldn't possible drive the car or obtain a license to do so - can (and they do) use a Waymo, just like they'd use an Uber, but they cannot do the same with Tesla "Full Self Driving".
https://www.autocar.co.uk/car-news/technology/mercedes-use-t...
That’s an interesting way of saying you live in London ;)
(Phoenix urban area is more populous than every urban area in the UK except for London)
According to Kagi the population of Greater Manchester is 2.8 million vs 1.61 for Phoenix.
Phoenix's metro population alone is 4.8m.
I think my point stands, that even large urban areas in the UK have no SDVs.
Countries develop at different rates on different things.
I live in a big city (larger population than Phoenix) in the Uk and I've never even seen a self-driving car. Anywhere. I don't even think such a thing exists on public roads in my country. That Gibson quote about the future not being evenly distributed, etc.
Just a data-point.