Already (kinda) in use: https://en.wikipedia.org/wiki/Micromort

Yeah it's sort of alarming when you think about hooking up models to take action in the real world and telling them it's just a game. Several scifi stories have it as a plot twist that humans think they are playing a game but are killing actual people. I'm not sure if the same twist shows up for AIs but it seems like an increasingly real possibility.

the target just may be on the scale of kills per cost.