I suppose someone liked Predator drones and usurped the name.
Someone high up enough in the company that no one would tell him that the name sucks for a fire engine.
Lifesaver, douser, super soaker, It is hard to come up with a fire truck name that describes what it does and sounds brave and daring.
Humans appreciate fire more than they dislike it, I suppose.
Civilization would not be the same without fire.