Then, if we start with the expectation that a human in the loop is necessary for live testing, we could have two. It reduces the impact of independent failures. It also adds some social pressure to avoid negligence. It also provides overlapping coverage, as a lifeguard in this thread has pointed out.
Humans are fallible. Accept that, and design systems to be safe despite individual errors.
Driving a car is not the same aa monitoring a self driving car. There will be differences in attentiveness. Stop equating them.
In my opinion, safe FSD cars are not possible with current technology on existing public roads - so either the technology has to improve by orders of magnitude, or the roads need to be modified significantly.
The gung-ho experimentation that is going on in public is in my opinion very dangerous and should be stopped, and this case is a perfect example of why.
Both the road infrastructure and other drivers are too crappy and unpredictable for FSD cars to be viable and safe.
Also this business of holding someone who is not actually controlling the vehicle accountable is ridiculous, and is surely something which will be proven in court eventually.
The experimental car shouldn't have been on the road at all if the only thing separating it from killing people is someone who is expected to maintain concentration for hours/days while simultaneously not actually doing anything.