Generally people want all the [other] criminals catching, but do not want all resources of the state used solely for policing. Optimisations then are preferred even if there is collateral harm.
Is it better to put boots on the ground, some of whom may die and who may cause collateral casualties in executing their mission, or a (hypothetically idealized) drone that kills only the target?
Still haven't decided if I have, or there even exists, a good answer to that.
A perfect drone wouldn't do that.
But on the other hand, a perfect drone has no cost of use, other than monetary. Which seems far too low a bar to set for the seriousness of taking a life.
I suppose a better question would be, why do you feel that in this particular situation - a murderer on rampage - you still feel that it is "deeply evil" to kill them in such a way that they "have no way to see it coming", to the point where you'd prefer other people to risk lives to do it in some other way?