All those "Volunteers" need to be housed and fed, trucks need fuel, batteries are needed, disposable supplies are needed, ropes and webbing need to be replaced after so many uses or hard falls, personal and team gear gets damaged and needs to be replaced, etc..
What most don't realize is the high costs involved EVEN THOUGH the search team may be unpaid volunteers. Often paid LEO's are on overtime to be on scene, the regular shift staff is needed for routine duty.
As a former volunteer SAR team member who worked both as a field team leader, and a team logistics officer, I've been personally and directly involved in mission costs, and expenses in SAR missions, and often the $$$ amount involved would shock most people.