That's false. The main reason Waymo is held up is because the accepted standard of driving is unsafe, and it has data and simulations that prove it.
For example, an unprotected left turn during rush hour. The gap between cars that people drive into in that situation often does not leave any room for chance. For example, if another car speeds up or changes lanes, there can be an unavoidable accident. But the standard for human drivers is to take those chances during heavy traffic, and drivers that try to avoid that are not accepted.
The issue is that people are incorrectly going to hold Waymo's computer responsible for some unavoidable accidents in those types of scenarios, but at the same time expecting them to make those maneuvers even though the computer knows there isn't enough margin.
That's not a weakness of the AI. That's an inability of people to understand the nature of traffic and the relationship between AI and people.