Earlier quoted context omitted.
The argument that counters this is that hailed rides will be cheaper than driving what you already have. You don't need to make a new purchase to switch. Even if you have a recent model sitting in the driveway, you may choose to save money by hailing a car rather than driving your own. I don't know if it'll play out like that, but the article is pretty convincing.
Why would a car owned by someone else be cheaper than the same car owned by you? The obvious answer - dividing the cost of the car over more miles - doesn't seem right to me. Driving more miles doesn't generally increase the useful mileage lifespan of cars, it just wears them out more quickly.
There's plenty of other things to break of course, but when the business model includes selling mobility the incentives are aligned toward durability and reliability (versus selling cars, which incentivizes planned obsolescence). It's worth putting in that extra 5% to make the car last twice as long.