If they can get into the drivers seat and attempt to drive themselves, surely they can get into a car as a passenger?

"The City (SF) has a fleet of transport vehicles that transport Seniors (old folks) around town. It would be much more cost effective to just have a bunch of Waymos available to Seniors."

this is what I meant.

The drivers of the fleet of transport vehicles are helping old folks in and out of the vehicles, which you wouldn't get with a waymo