CalSTAR can fly Paramedic/RN teams like REACH and others, but they choose not to. I used to have almost daily face to face contact with their crews. Their RN's were quite happy with the 2 RN crew...
I haven't worked with those folks... Mostly I worked with CS2 until about 2003 or 2004 to assist them with ground transport at one of the hospitals in that area. Because of the type of calls (and having 2 of their RN's as my instructors) I got to know them pretty well. Believe me, they do their fair share of griping about "work".
I suspect that the Medic only needs to be accredited in the county where they're based out of, and their response would be treated as a mutual aid, so they only need to utilize one set of protocols. Dual Nurse is a lot more flexible in that their Medical Director sets the protocols and each county they operate in just signs an agreement that CS can use their own protocols instead of the Paramedic Protocols, due the expanded scope of the Nurses and they don't have to work with a partner that has to use a different set of protocols. I imagine that all flight programs set up their RN protocols this way.