> slow (especially because USians oppose optimal stop spacing) and dirty

It’s slow because it must solve for many possible routes. Cabs are point to point. A rideshared cab, moreover, knows ex ante where its customer is going and, in a city, where its next customer is.

Tiredness is a big one. I was driven by a guy who had worked nonstop for a whole weekend. It was one of the most terrifying drives of my life. I had to tell him to park and sleep outside my house, or else I would report him to Uber.