Most of the matched FMGs have spent significant time in the US and got letters of recommendation from US faculty. That should go a long way to quell anxiety about their unknown med schools. I don't think you can dismiss the political dynamics as easily as you're doing here. It's interesting that the places most open to IMGs tend to be the very top programs can afford to be choosy or the lowest who wouldn't fill otherwise. And it's not an issue of fairness. Medicine is not the most international thing out there, and the US is actually still one of the most open countries to IMGs.
I do think that you can dismiss the political dynamics as easily as that. I don't think any program director even thinks about those dynamics. It's not that they're all benevolent Good Samaritans, but rather that they just want what is best for their residency program, and maybe for the affiliated medical school. A PD might give a bump to a person from the affiliated med school in order to benefit their own reputations, but they don't care about advancing the stature of other med schools. Their primary incentive is to get the best residency class.
And to get the best residency class, you pick the people who you know will be able to succeed in your system. Most American med school graduates are pretty good residents, so it's a safe bet. Many IMGs come from very different cultural backgrounds that make it difficult for them to succeed in the same system. Many of them come from a country where psych rotations aren't required in med school. Many others come from countries where you don't actually touch any patients until you're an intern. Many others come from places where med school is focused on treating 3rd-world problems, and while they may be spectacular at recognizing the various manifestations of TB and malaria, they may not be as familiar with working in interdisciplinary teams and in a system that requires good communication to ensure good patient autonomy. While 80-90% of IMGs may understand these issues and handle them appropriately, I'd expect that the same is true for 90-95% of AMGs, thereby making them a safer bet. Most PDs would rather have a low-risk-low-reward resident (i.e. below-average US med student) than a high-risk-high-reward applicant (i.e. stellar IMG with great scores, lots of publications, but poor communication skills in English and/or poor understanding of how we deal with ethical/other issues here).
For instance, I knew a guy from India who was applying to IM and had trouble finding a spot despite having great scores and great background otherwise. I kept telling him that he needs to work on his English skills instead of spending all of his time working on low-yield research. He refused to go watch American movies or do other similar things, because he was too busy doing science. I told him about how my dad (who came from Pakistan) learned to speak American English by reading American comic books, and then looked up any words that he didn't recognize (i.e. he didn't know what "spooky" meant). This guy agreed that his English was weak, but refused to improve it because he didn't think it was important.
I know another doctor in PM&R who knows nothing about psychiatry - giving her the benefit of the doubt, I'm guessing she went to med school in a country where psychiatry isn't really taught. She thought that schizophrenia just means that the patient is violent/dangerous and that antipsychotics are just chemical restraints. She didn't want to accept my patient to a physical rehab facility because he's on an antipsychotic, and she thought that he must be dangerous (which is not even remotely true) - and she definitely couldn't handle somebody who is getting IM antipsychotics, even if it's a depot injection, because she thinks that you only inject antipsychotics (including depot shots, even though she didn't know what that is) if patients are agitated. I told her that if she doesn't want to deal with giving the patient his Prolixin D, then I can switch him to Haldol, since it lasts 4 weeks instead of 2, and they therefore wouldn't have to deal with it at the rehab facility. She said "oh no no no no no"... she can't have a patient on Haldol, since that means he's dangerous... but it's OK as long as it's Prolixin because she doesn't know what Prolixin is.
