Yes, I share this concern, and I would hate to be the patient who finds out the hard way that their prescribing psychologist isn't up to the task of identifying a medication interaction. There will always be fewer practitioners who actually identify such events than who should be able to identify them, but if that ratio is meaningfully higher for physicians than for non-physician prescribers (and I believe it is), then prescribing privileges need to be handled very carefully.
Hypothetically I could get behind an "extender" model where, working under a physician-supervised protocol, a psychologist could do something like refill a non-scheduled prescription for a stable patient. I just don't see the value of that for my profession, frankly. I didn't train to be a midlevel. My standard for independent practice is to be competent to manage, from start to finish, the realistic spectrum of positive and negative outcomes of any treatment I provide.
Some comments I have heard from inexperienced psychologists or trainees, especially those who have had little exposure to working with other disciplines, concern me. Fortunately it's been very infrequent, but I have encountered people who say things like "I went through 6 years of doctoral training in psychology, so I have the same amount of training in mental health as a psychiatrist," and they just miss the point entirely. Just cringeworthy. The worst kind of hubris is the kind that comes from being unable to fully conceptualize what could go wrong.
Working closely with medical subspecialists has made me appreciate that level of expertise. But it's having had the tables turned a few times that has driven it home for me. Because I have expert knowledge in a very specific area (which took years to acquire, mostly in the context of research), I have been able at times to catch something that eluded a physician in a shared patient. It has nothing to do with my being a psychologist specifically, and everything to do with the fact that in this one circumscribed area, I have knowledge that most clinicians don't. So I respect immersing oneself for years in a specialty to become competent at it, and it frustrates me to see it devalued.
If a licensed prescribing psychologist can pass the ABPN exam, I will revisit my opinion.