Humans understandably are extremely averse to the idea of dying for a stupid reason, especially if control over the death is shifted away from the person, in which case they are more "furious" than "averse". It's why we hate drunk drivers so much. If I introduce a car that reduces deaths to near zero, but the remaining deaths are caused by a robot arm that is programmed to pop out and stab the driver, people are not going to accept that. If my car reduces car deaths dramatically, but the remaining deaths are caused by the car killing you by accident in an extremely dramatic way that you are confident you would have avoided if you were driving, e.g. swerving off the road and driving at full speed into a median, or into a truck that you can see but the car can't, people are not going to accept that either. You can not shift a person's ability to protect themselves away from themselves and occasionally kill them with your solution simply because your system is better than the average across all humans, even if it's much better.

It's frankly a little baffling that this part of human psychology even has to be explained. It's like the trolley problem: There seem to be some people who don't understand why you wouldn't simply pursue the result that holds fewer deaths - who don't understand why the trolley problem exists at all, what the point of it is. I suspect there is a relationship between these people and the people who don't understand how there could be any part of decision-making about autonomous vehicles apart from the raw numeric value of deaths vs non-autonomous vehicles.