Reality is boring. The drones will be used for surveillance but the death will be delivered by regular firearms. The holocaust was "expensive" enough to justify shipping people into a central location where they are executed as efficiently as possible. What makes people think that a government would be willing to spend $5000 per killed civilian when it has to kill hundreds of millions?

I agree, with one correction: majority of Holocaust victims never seen a camp (neither concentration nor death camp). They were executed with regular firearms near the place they lived.

Camps were for undesirables that for whatever reason couldn't be killed immediately. Mostly because there were too many of them in one place.

See https://news.ycombinator.com/item?id=28797055