Wow. I cannot fathom the thought process involved here.
The RN's in ER here are required to take ATLS (Advanced Trauma Life Support) which is pretty much based on prehospital care. They are certainly qualified to collar and board a patient in a parking lot. I can't count the times working in the ER as an EMT how many times we went out under the canopy to help someone out of a car or off the concrete. Our EMS here is actually in the hospital parking lot not 50 yards from the ER but would not be called for that I dont think.
I have responded to a 911 call from the payphone in the ER waiting room.

The patient didnt get the narcotics she wanted for her sore foot and wanted to be taken by ambulance to another ER. We took her only because the ER Doc threatened to shoot us if we didnt take her somewhere. A few hours later an AMR ambulance shows up and drops her off under our canopy where she calls someone to come pick her up. The other ER gave her Ibuprofin as well. 2 ER visits, 3 ambulance runs later and all she had to show for it was 2 scripts for 800mg Motrin.