Nige321 - or perhaps because there are some realities to searching that have been learned through long experience both on the ground and in the air.
The search is one part of the equation and without the rescue asset nearby becomes pretty pointless if life is at stake.
I'd like to see the drone search in a 200' cloudbase over steep wooded terrain in the dark or in heavy rain at 100' over the sea at night or in blowing snow or 60 kt winds - many SAR boys and girls have done all of these and much more and a model aircraft (no matter how much you polish it and roll it in glitter) just won't cut the mustard.