In addition to what has been said, the Military Flight Doc, while on active duty, are not authorized to give Class 1 physicals. As my flight doc explained, it's a way for the medical community to insure employment. They realized many airline pilots were retired military pilots who could get their physicals through the military. Rather than give up on this lucrative pool of required physicals, the AMA in concert with the FAA prohibited Active Duty Military Flight Docs from performing a Class 1 physical. Class 2 & 3 physicals are performed by a select group of flight docs. I say select because the flight doc has to take the initative to register with the FAA and then complete the paper work. That is why not all docs are authorized. It's by choice.