"Since 1943, AAPS has been dedicated to the highest ethical standards of the Oath of Hippocrates and to preserving the sanctity of the patient-physician relationship and the practice of private medicine."The "private" is a give-away, to me at least. Back in the day the American Medical Association was a pillar of the fight against socialized medicine. But my suspicion is that they didn't fight strongly enough, so a splinter group founded the AAPS to be more stalwart.
(I swear until I started writing this 10 minutes ago I hadn't checked the wikipedia entry.)