One difference is that if it were found that a psychiatrist or other professional had encouraged a patient's delusions or suicidal tendencies, then that person would likely lose his/her license and potentially face criminal penalties.
We know that humans should be able to consider the consequences of their actions and thus we hold them accountable (generally).
I'd be surprised if comparisons in the self-driving space have not been made: if waymo is better than the average driver, but still gets into an accident, who should be held accountable?
Though we also know that with big corporations, even clear negligence that leads to mass casualties does not often result in criminal penalties (e.g., Boeing).