It looks like Tesla is actually calling it a "ride-hailing" service (not a "robotaxi" service).
Not sure how this is different from calling for an Uber or Lyft and getting a driver who owns a Tesla with FSD. Probably Tesla's service uses a more sophisticated version of FSD than what is available to regular Tesla owners. However, it still seems more limited than Uber/Lyft, at least for now, because Uber/Lyft aren't geofenced and don't require invites.