But Waymo or their competitors are not in the "shuttling people around" business. They're developing a driver. Robotaxi is one of the applications.

The winner-takes-all aspect comes from economies of scale for example. If Waymo is several years ahead and has better economics, how can Cruise catch up? They will have lower cost of capital. Top people will want to work at Waymo rather than Cruise. It will be hard to close the R&D gap. When Cruise is where Waymo is today, Waymo will already have a lightweight package that will be used by Ford, VW or Toyota and capable to drive everywhere in any weather conditions.

I don't know how you can write that list and come to the conclusion that it's not winner-take-all. In their home market (US), Uber is ~75%, Lyft is ~25%, and all other competitors are sub-1% combined. Didi is similarly dominant in China, and so on. "Completely different markets have different winners taking it all" does not counteract the claim of winner-takes-all in any way, nor does listing utterly insignificant players like BlackWolf. Do you think people saying "winner-takes-all" in business contexts mean one company with literally 100% marketshare globally?