Anyone who has taken a psychology course can understand why this is the case: the only people who stay in psych are the ones that actually believe the bullshit that psychology teaches without questioning it. The entire psychology curriculum for years was (and still in many ways) is based on memorizing results from received authority, and not based on method like it is in the real sciences. Even biology, which is heavy on memorization explicitly deals with methods at every turn.

Psychology has always struck me as mostly boulder dash, but psychiatry is supposedly better. On the other hand medicine seems to be a very authorian discipline in general.