Although I wonder if seasonality is important here - obviously Phoenix isn't Minnesota but could driving conditions have been worse in Q1 compared to this summer, from the perspective of a self-driving car?
An example from my most recent drive: I drove through a common where cows graze. I doubt a driverless car is programmed to slow down near cows.
The only solution I can see is to whitelist roads and start with the simplest (motorways/highways) then gradually expand to more and more roads. I guess that's kind of what they're doing - suburban America is very easy (although you still have pedestrians and cyclists to deal with unlike motorways), and maybe whitelisting is the cause of the routing complaint.
The whole "if it's not amaaaaazing it's terrible" thing is idiotic.