There is no shortage of practitioners, ie ~medical middle managers such as myself and other MDs/DOs/NPs/PAs, willing to work in the ER.
(In the narrative of one faction, the suits have in fact created a surplus of us, including docs, that will only get bigger in the next 5 years, possibly hitting n=10,000+ surplus ER docs by 2030. If that happens, a major reason for that in this narrative would be that the suits have directly funded more Emergency Medicine residency slots opening in that time than there are interested American medical students applying to the specialty.)
There is no shortage of bureaucrats willing to shuffle paper and create more work for themselves in the name of Quality or whatever. See this doc's blog for a relatively balanced take on this growth, but I do think there is truth to his first graphic: https://investingdoc.com/the-growth-of-administrators-in-hea...
In my understanding, there is a critical shortage of RNs willing to provide the actual hands-on patient care, for pay that will still turn a profit for the hospital.
This includes skilled ER triage nurses.
But the other side of the coin from labor shortage in this problem is, again, that hospitals simply are not reimbursed sustainably to serve many ER patients, particularly self-pay patients, in the non-literally-emergent ways that those patients should be served, would like to be served, or deserve to be served medically.
Ie, in my understanding the ER is often a loss-leader for a hospital that serves to get patients into higher-total-reimbursement clinics such as GI, cardiology, and orthopedics.
Again, I'm not trying to argue for any faction here including doctors/midlevels, RNs, hospital admin, or even patients. I'm just trying to describe the system from my view down my periscope over 8+ years of doing this.