Right. Usually your bizarre logic, no feature should be released until it is proven 100% reliable, safe, and impervious to human mistakes. No such system exists or will ever exist. Let's not forgot the fact that the driver is ultimately responsible for safety at this time.
Except nobody is claiming that a system needs to be 100% perfect 100% of the time. Obviously that is unrealistic. The issue is whether the fault was responsible for the accident or not. That's why accidents are investigated, to figure out exactly what happened and whether a defect or flaw was responsible for the accident or not.
But frankly, I find this whole argument that the driver is responsible therefore we should not question the technology to be bizarre. Yes, the driver is responsible since AP is L2. And yes, no system is 100%. But we should still try to prevent future deaths if possible. Just because no system is perfect, does not mean we should just do nothing and let more deaths happen that maybe could be prevented. And a better driver monitoring system would help make AP even better and even safer. So that should be explored as well.