"Phoenix is the capital and most populous city of the U.S. state of Arizona. With 1,626,078 people (as of 2017), Phoenix is the fifth most populous city nationwide"
Explain the criteria you used to classify it as "suburbs".
Phoenix is the first metro area to launch the service.
Waymo (and others) are testing in other places.
From https://waymo.com/ontheroad/: Kirkland (lots of rain), Bay Area (including San Francisco), Detroit (snow during winter), Atlanta, Austin.
I don't see how you arrived at the 1% and 1% of what?
If it took Waymo 10 years to drive in Phonix, Arizona, it'll take them 1000 years to improve enough to drive in Detroit?
Those things are pretty binary: either they can drive autonomously or they can't.