Having done my time carrying out many casevacs (military, police and civilian) I've been fed a line on a number of occasions.
Very early in my military career as a junior and recently qualified pilot I was tasked at night (in the days before night vision devices were available) to rescue a soldier "with a broken back" from the Belize jungle. We came close to busting our backsides to get there; not least of all we flew through a tropical thunderstorm to locate him. When we arrived the soldiers had done nothing to light the site for us. The entire patrol walked to the aircraft to be extracted. The one with the "broken back" walked onto the aircraft with the rest of them....
Another occasion - I was tasked after midnight to an unlit site to rescue a casualty "with a severe hand injury". Again, during a tropical storm, the Far East this time. When we found the casualty, he was at a beach party, drunk and and had a cut on his thumb after breaking his glass; the likes of which many sensible folks wouldn't have gone to A&E for.
Sometimes it's not worth risking the aircraft, crew and casualty; but you often don't find out until after the event - that's just how it goes.