It doesn't seem substantively different from destroying a target via long-range missile or via a laser-guided bomb dropped from a human pilot flying thousands of feet over head. All three are impersonal ways of killing other human beings from a mostly-safe distance – especially in our modern asymmetrical engagements.
I agree that it feels gross to imagine a soldier sitting in a skyscraper pulling a trigger to kill people half way round the world, and it feels odd for someone to kill people in the morning and go home to sleep their bed that night, again and again, day after day. But military commanders have effectively been doing that since we've had faster-than-horse battlefield communication. So, I'm not convinced this is some brave new world of impersonal killing.
HOWEVER, I get the problem with drone warfare. Drones provide commanders with several benefits (no human casualties on "our" side, generally great accuracy, relatively low cost, etc.) that let them scale up the killing with minimal public outcry. This seems a real problem.
I guess my point is that the problem is not drones. The problem is killing so many people with so little oversight and so little apparent concern – whether by Cruise missile, drone, nanoswarm, T2, whatever.
I'd reword your sentence to be: "how we collectively became accepting of our governments casually killing our fellow humans half way round the world is remarkable"
http://www.salon.com/2015/03/06/a_chilling_new_post_traumati...
https://www.theguardian.com/world/2013/jul/28/life-us-drone-...
Well, for the rest of the world, state actors wreaking havoc with drones and AI with inpunity is already a problem.