Truth be told, IMO, I don't think a typical FP residency prepares a typical FP resident to hold down a level 1 trauma center in a high-acuity-high-volume urban academic ED. The number of half-days in continuity clinic over 3 years just doesn't transfer to the number of shifts EM residents do in the ED. Certainly, an FP resident can acquire that experience by taking additional shifts/electives/fellowship/moonlight and work successfully in the ED. At the end of the day, and this is true for all types of privileging, it's the experience that counts, not the specialty designation (e.g. not all ID doctors are knowledgeable of HIV... can you imagine?... it all depends on their exposure during fellowship... not all ortho's can do hand or spine... etc.)
That said, while FPs may not be the "best trained" to work in the ED, don't assume that EM residents get "the best training." It's far from perfect. How can EM doctors who train in the ED, med-surg floor, and ICU make decisions on who can or cannot go home to be managed on an outpatient basis? I don't understand that. They don't spend enough time in primary care clinic, or SNF, or LTACs, or Nursing Homes, or any other setting where a CT scanner is hard to come by. And they think it's useless to them, if you ever talk to them. How often have you stood in the ED and said to yourself, if this exact patient had presented to my clinic, I would have approached it differently? Because EM residents don't follow patients onto the floor or into the outpatient setting, their training is like doing algebra without ever looking at the answers. It's not all their fault. A system that rewards docs for speed but punishes them for inaccuracies, leading to sloppy work, inappropriate treatment, and high malpractice costs, only exacerbates the problem.
So, sure, ok, maybe the typical FP's not qualified to work in an urban ED, but EM docs can learn a thing or two from FP's.