It generally doesn’t snow in SF or Chandler. I personally like snow, so I wouldn’t describe that weather as significantly worse. But my understanding is snow makes it hard for lane keeping, and then there’s all sorts of edge cases like streets that aren’t plowed and require special driving techniques, people placing cones to reserve parking spaces, etc.
I feel like San Francisco is a good progression - still generally good weather, but much more crowded, more traffic, more special cases, pedestrians and bikes, one-way roads, topography, limited visibility due to hills and no-setback buildings, construction, buses, etc. It's a significant leap in urban complexity, probably greater than 98% of the rest of the USA.
Regarding the weather, lots of people have mentioned snow, but much of the Midwest, Northeast, and especially the South can have sudden torrential rain. I haven't researched it but I would guess that a Florida rainstorm would be hard for both radar and visual guidance. I predict their next city will be Orlando, in partnership with Disney. Then somewhere like Boston (harder - older street pattern and more snow) or Philadelphia (easier). Each of those 3 would "unlock" new territory they can cover. I predict that NYC will be one of the last areas "unlocked".
So the vast majority of the US has either significantly worse weather than SF, or a significantly harder ODD than SF?
Could you elaborate on that?