Vargohoat
You're thinking about this the wrong way. There's immense value in getting _any_ commercial service out there, not just in PR but in a full end-to-end test of all the ops/logistical/product/etc that come from having to deal with customers in reality. A good chunk of a decade and billions of dollars have been poured into the research behind these services. I doubt anyone at Cruise or Waymo cares or even expects these limited services to be profitable, but that's entirely missing the point.
I doubt they're going straight for the meatiest market. A commercial service of any sort would be a huge coup for a self-driving car co (as the Tempe launch was for Waymo). In SF's case, it also provides a foothold in a market that's actually economically sustainable. Once the technology reaches the point where more complex and crowded scenes can be handled safely, expanding is relatively trivial compared to spinning up from scratch.