"Meat shields" has a nice physicality to it, though
What I had considered is that in the case of self-driving cars, nobody is criminally accountable, even though the rest of us may be criminally negligent should we make some horrific error. Philosophically, there is some kind of reason that criminal acts require punishment beyond mere financial liability (e.g., prison time) and self-driving cars are exempted from this. Currently, self-driving cars are also exempt from the actual laws of the road because the police are dis-empowered to enforce anything on the self-driving car.
Whether the tool is too powerful or ethical to use is an orthogonal discussion, in my opinion. Taken to the extreme, nuclear weapons still need someone fire or drop them. (We should still have discussions on safety and ethics always!)