It is the only such device in either game that can be used an unlimited number of times (subject to supply credit availability), since other healing items like Life Vendors and Reversers cannot be reloaded. NPC soldiers will never get in a Caravan no matter how injured they are, even if they have been recruited by the Air Raider driving it. The only way for it to be heal anyone in singleplayer is if the Air Raider gets in the back himself.