The introduction of self-driving technology at scale will inevitably result in a few accidents no matter how many sensors are used. It's the same with every new technology deployed in high-risk situations, including motor vehicles themselves. Even malfunctioning airbags have caused fatalities. The important thing is to identify the issue early so the company can address it before more people get hurt, which the ODI in this case is thankfully doing.
There is still no excuse for not using LIDAR in addition to anything else.