Those are some good points. Waymo & self-driving cars only makes sense in markets where the cost of paying a human driver is much higher than the amortized cost of operating a self-driving vehicle. As an extreme example, in Bangladesh a driver will work for ~$0.25/hour. Self-driving cars don't make economical sense there, the additional cost of making a vehicle self-driving never pays off vs having a dedicated driver.
Waymo can expand easily in markets like SF and NYC, where drivers are guaranteed a minimum pay rate of $22+ per hour, but will make less and less economic sense in cheaper labor markets.
I believe sooner or later Waymo will start selling their tech package to car companies, who in turn will pass the cost on to customers either as a huge mark up or subscription services. I don't believe Waymo can survive on self-driving taxi alone, the hardware cost is too much to go global.