I watched a special the other night... In Mosul, the baddies were stalking and trying to assassinate an Iraqi general using cheap drones armed with hand grenades. He had to be careful about exposing himself, they were looking for him.
And of course, the drones are relaying video of troop movements and locations. So the important thing isn’t the cost of the drone, but the cost of the target, or the value of the information they are surveilling.