This phenomenon is interesting, and a bit surprising. I can kinda see it: while my experiences with Uber & Lyft over the past ~13 years has been overall very positive, there are quite a few minor-seeming-but-adds-up-to-annoying things that can happen with Uber/Lyft that just won't happen with Waymo: * Driver cancels and you have to wait for a new driver to accept. * Driver is really chatty and you aren't in the mood,…
I don't see how Waymo would be immune to the unpleasant smell issue. It might happen less frequently, but it'll definitely happen.
For an Uber/Lyft driver, if they're even (made) aware of the problem, they'll probably not take care of the issue until they've finished their day of driving.