Well, it's not quite so easy. You can have drones for orders of magnitude less cost than full on helicopters/planes...say $10-100K/drone instead of $10M/plane. Plus they can fly in inclement weather with no risk to humans. They can stay "on station" for days instead of hours. You can use 100s or 1,000s of them to search an area non stop until the mission is complete without having to have 1,000s of pilots ready to go at a moment's notice.
When drones start being used to evacuating people from disaster areas, they will be able to perform more risky landings without risk to pilots.