Pretty much everyone we rescued with Tahoe Nordic SAR made some kind of contribution afterwards. A few became search members, some helped with fund raising or education, some just gave a whole bunch of money. Even the most bone headed people had such a challenging experience they were super grateful for the help.
Helicopter rides are not usually free as the laws say commercial ambulance services must be used first if practical. The military ones are used if their special machinery is needed or if the commercial ones aren't available.