>It’s not clear why someone would be a tied to Waymo if another equally-available self-driving taxi were available that were substantially less expensive, even if it were marginally less safe.

Do not underestimate quality of the experience/product on the whole. Whenever I take an Uber/Lyft/Taxi, I find myself in the uncomfortable position of having to deal with a stranger in a small space for a period a little longer than an elevator ride (if you know what I mean)... and that driver in turn has to figure out how to interact with me (or not). We're social animals and we feel compelled to do something or to expect something even if that interaction doesn't come. In a Waymo this forced social situation doesn't exist: and I for one find it superior enough to pay the small premium... which in my experience is on par with what I'd have to tip (another fun thing to have to deal with in the Uber/Lyft/Taxi scenario).

Also, I've mentioned this recently elsewhere. Uber/Lyft/Taxis don't always show up, drivers cancel trips and that can happen several times in a row. Waymo hasn't done that to me yet. So the certainty and dependable expectation setting of Waymo vs. Uber/Lyft/Taxis make a compelling case for premium pricing. And again, in my experience, the pricing of Waymo hasn't been so much more than the alternatives to justify calling those alternatives "substantially less expensive". Once the tipping is figured into the equation they're roughly on par.

Would I consider other self-driving entrants over Waymo? Sure if they can match the quality of service and are price competitive. But the comparison with traditional driver based services needs to account to the higher overall product quality and not just the pricing model or even safety margins (so long as they are within some reasonable baseline).