A significant portion of US highways and backroads are uncovered by cell signal. I suppose a self driving car would have starlink these days.

We once had no gas stations, now we have 150,000 (in the US). If the commercial need is there, building out connectivity is an unlikely impediment. Starlink et al. can solve this everywhere except when there's severe weather, a problem Waymo shares, which is starting to make me think the Upper Midwest might be waiting a very long time for self-driving cars.

I think the bigger problem is mapping every road to the detail they need and keeping that up to date.

Did I argue that the technology was not viable?

I answered the question 'What does Waymo lack in your opinion to not be considered "full self driving"?'. And clearly its not if it can't drive on literally 99.99% of roads in the world. Any argument to the contrary is just ridiculous.

As I said above, "full self driving" is clearly an outdated concept.