All their sensors didn't prevent them from crashing into stationary object. You'd think that would be the absolute easiest to avoid, especially with both radar and lidar on board. Accidents like that show the training data and software will be much more important than number of sensors.
I don't mean Waymo is bad or unsafe, it's pretty cool. My point is about true automation needing data and intelligence. A lot more data than we currently have, because the problem is in the "edge" cases, the kind of situation the software has never encountered. Waymo is in the lead for now but they have fewer cars on the road, which means less data.