I’m a million miles from this area, so I’m interested: [why] is a machine killing people more immoral than people killing people?
This argument is fatecious and irrational. You can argue whether it's acceptable to kill. Beyond that it makes rigorously no difference whether you kill someone with your bare hands or by pressing a button.
There may be ethical questions in war, but I don't see why the mechanisms should matter. Perhaps it should but you haven't even come close to making that case.
Maybe my bad for assuming that any reasonable person reading wouldn’t need it stating that killing people is, yes, immoral. And given this shared understanding, the root of my question was why a machine killing people is more immoral.
Generally speaking, over time we have become much more accurate at targeting specific people to kill, but we are still a very long way off from 100% accuracy, and none of the issues you raised are particularly novel to drones.
I would go a step further and point out the fact that while bombs are fired and aimed, landmines are designed specifically to kill and/or main indiscriminately.
By detaching the moral choice from a person it makes killing more acceptable.
At least that's my take.
People are going to bat eyes in the advent of these weapons as well. That is not going to stop Pentagon, China, or Russia from using these weapons.
One issue could be that they are not as reliable as target seekers as they are good as target destroyers. And plenty of mistakes have been committed by humans in charge.
Whether autonomous weapons system will be better than seeking and killing enemy combatants rather than innocent people is something to observe.
Right now, autonomous systems are very very unreliable at this.