Overall, I believe Rx psychology is bad for public health. Not because I believe psychologists will be inadvertently killing people left and right -- hell, a handful of high school kids have posed as physicians and treated patients in many settings, including ERs, over reasonably-lengthy periods or time without any evidence of adverse events. I find it highly unlikely that people will be dropping dead when some psychologist starts prescribing Zoloft. The biggest problem is this false narrative in society about the greater need for psychiatric medications and the continual overselling of ideas that perpetuate society's external locus of control. The biggest problem I deal with on a daily basis and the largest barrier to clinical improvement, bar none, is the externalization of problems and the reliance on external sources of validation for inward problems. The analogy of diabetes is rather appropriate. Type I and type II are very different fundamentally but ultimately have some similar outcomes because they both fall under the diabetes umbrella by virtue of elevating blood glucose levels. There are certainly things a type I diabetic can do to modify many of their risk factors but it is certainly a disease that can just happen upon someone. When society blurs the lines between the two, we make assumptions about diabetes as a whole and start to de-emphasize lifestyle modification in favor of a disease model. Only 10% of diabetics are type I. I'm kind of going off on a tangent here, but irrational societal beliefs help accentuate and perpetuate a very strong external locus of control. I see Rx psychology as similar to a personal trainer at the gym wanting the ability to prescribe insulin to type II diabetics. The personal trainer -- functioning as a personal trainer -- will have more power to help the individual as well as society by assisting that person with personal improvement through training and not inappropriately prescribing insulin. Every time some antisocial shoots up a public space, we hear cries for more mental health funding. Many people in mental health fields eat this up and use these tragedies to push this agenda, too, but we all know it's nonsense. We believe in mental health treatment, but not necessarily for preventing willful human behavior, but many are willing to hide behind that to push agenda. So too Rx psychology.
The other questions that must be asked is which populations are being targeted with this? To read the political narrative would reference that difficult access to psychiatrists -- which is really more a problem of treating the "under-served" or, more specifically, severely mentally ill populations -- are the targets. Are psychologists looking to go in to community mental health centers and treat people with schizophrenia, manage long-acting injectables or maintain someone on clozapine? Are they going to manage medications for a person with multiple hospitalizations for mania who had to be taken off lithium because of CKD and also has Parkinson's? Or are they looking to supplement psychotherapy with Prozac? Or offer different augmentation and polypharmacy that a PCP would not? We all know that Rx psychologists would, or most likely should, recognize the limits of their training and, with some small exceptions, I'm sure, would not be treating a lot of the SMI or medically complex. Even the DoD psychologists were prescribing antipsychotics <10% of the time. One of my questions is, of those in, say, rural Idaho, who have access to a psychologist, what percentage of those don't also have access to a PCP? If this is the population Rx psychology is looking for, I wish they'd just say that and argue those points in the political sphere. But, of course, as this is political, it's being sold on how important access to care is and using populations that the Rx psychologist won't be seeing as justification for advancing this agenda. Seems to play out like a bait and switch.
To accept the idea of Rx psychology you have to accept a few false premises:
1. There's a shortage of access to psychiatric medications.
2. This shortage of access to psychiatric medications is adversely affecting the population (they even reference suicides in this Idaho link in OP).
3. Expanding the scope of practice for non-psychiatrists to prescribe these medications will help alleviate this problem.
4. Current state regulations in Rx states is sufficient criteria for psychologists to effectively step in to this role.
If we're talking about lack of evidence, there's absolutely no evidence for any of those premises. I guess it's the AMA's job to prove those premises aren't true?
with the machines. 
