Like akf said, no, an RN being an RN doesn't instantly trump me as a medic.
If the RN is part of my agency, and they are a CCRN, then yes, they are in charge of the patint.
If its not a nurse from my agency, but say an RN at a nursing home that we were called to, sorry toots, I'm top dog.
Heck, I work with several RNs at standbys, and there's just an understanding that neither is "in charge", we work off each others skills and knowledge. Cardiac or trauma? The medic tends to lead. Complex medical? The nurse tends to lead. But key word is "tends" as medicine, especially field medicine, is fluid.
Really, cert level is irrelevent after a point. Do you really think people like vene are less capable than a newer nurse just because he's a "lowly medic"? Base education is different, sure, as were a speciality whilst RNs are educated as generalist, but anyone who doesn't continue to learn after school shouldn't be in medicine anyway.
Heck, having an MD after your name still doesn't give you ultimate authority over me. The one and only doctor I'm required to listen to is the one that signs my protocol book. Any and every other doctor I encounter, I can utilize for the benefit of the patient, but don't have to follow.