Who do you expect will find FSD-enabled Robotaxis useful? I'm not sure the concept makes any sense outside of the inner city and densely-populated areas, both due to demand for the service and logistical realities.
Especially if we're talking consumers having their vehicles out shuttling people around when not being used, this will surely need to be limited to shorter distances and timeframes. Even then, I'm not sure how you juggle this with the timing and demands of the vehicle's owner, who might request the vehicle be returned at certain times or on short notice if they suddenly end up needing it for something. What if it's occupied, and what if it's out in Timbuktu or with an occupant who wants to make multiple stops and/or refuses to give it up at that moment?
Are Tesla's seats equipped with the hardware to support an "occupant eject and vehicle return" function? Either way, you presumably wouldn't see consumer FSD Robotaxis out doing long rural routes or even suburban milk runs far away from home base.
There are seriously so many questions around how this would even work