Maybe this is because groups that adequately prepare themselves are also relatively safety-conscious and don't get into trouble in the first place. The fact that you are isolated and far from help should inform everything you do, whether that be handling hot pots over a fire or running a rapid.
Prevention is a much less painful and expensive option than a wilderness medevac.
Proper preparation is crucial for wilderness first aid . Take a first aid course before your trip - it is pointless to have a well stocked medical kit if you don't know how to use it. There are many excellent first aid courses available through St. John's Ambulance and other organisations. The dilemma is that most first aid courses assume that the ambulance is 10 minutes away and that the victim can swiftly be transported to a hospital. Try to find a wilderness or backcountry-oriented course if you can.