Since I have been called a "dirty rotten guild monopolist" on my own blog, I thought I should try to live up to the name.
Psychologists have been trying to get prescribing privileges in various states and they have been consistently shot down. I can understand that psychologists would like to prescribe, given the difficulties of finding psychiatrists and the low regard they have for primary care physicians. But I did take a pharmacology course and prescribe something at least ten times a day (well less, but that's closer to the national average).
If a patient experiences an adverse event, I am in a position to treat or direct the patient accordingly. Enough people dump on me as it is. If it's your adverse event, don't refer the patient back to me. On the other hand, if you think your patient really needs a medication, I'll take your recommendation, if you ask me first.
My opinion; to understand why psychologists would like to prescribe rather than foster the primary care relationships they should be supporting, just follow the money.