I work (part time, per diem) at Transcare in Dutchess and yea, they don't hire unless you're 21 either. It mostly has to do with being able to drive. They need both partners to be able the drive the ambulance, that way one isn't being the EMT or medic all shift, while the other drives the whole time. I also believe that their insurance has a clause saying noone under 21 can drive company vehicles. Not absolutely positive on that one though.