Why Drones Win
As I see it, one must separate the question of whether a given person ought to be killed (morally and legally speaking) from the question of how this should be done (i.e. using what tools), if s/he is to be killed legitimately. As I have suggested elsewhere, compared to other tools – whether Special Forces, missiles, or bombs – drones are the preferred means by far. They allow for a much more careful review of the target, limit collateral damage, and reduce the casualties on our side.
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Given these facts, it seems odd to me for anyone to imply that drones should not be employed because of the danger of contagion. If other nations use them for legitimate kills, more power to them. If they use them for illegitimate kills, it would not be better or worse than if they had used other technologies (see Syria). And if they use drones to achieve goals other than killing terrorists, so be it. (Some are now used for locating lost skiers...)
The notion that if the U.S. did not develop and popularize the production and deployment of this technology that other nations would not do so, is questionable. China, for instance, is "popularizing" anti-ship missiles (followed by Iran) and cyber spying (followed by the U.S.). The question ought to be whether the goal is legitimate, and whether the means are preferable to others. In terms of morality and efficiency, drones win, hands down.