Why has Waymo taken so long to commercialize autonomous taxis?

ARK Invest has a good article, “Why has Waymo taken so long to commercialize autonomous taxis?,” in which they write about System Identified Failures and Unexpected Failures.

One interesting note from the article that has nothing to do with Waymo: “Some stretches of road are trickier and some intersections more difficult to navigate than others. In Los Angeles, for example, roughly a quarter of pedestrian collisions take place at only 1% of its intersections.”