Simply cause the main reason behind the ''Match'' is to get the ''best doctor'' for the patient. NOT CAUSE THE PATIENTS ARE MOSTLY AMERICAN, IT HAS TO BE AN AMERICAN RESIDENT. WE ARE NOT IN MILITARY OR RUNNING FOR PRESIDENCY.
A few points, most of which thedrjojo has already made or at least intimated.
First, you do not need to be an American citizen to be in the US military; officers need to be US citizens, but enlisted soldiers are not so limited.
Second, I would venture that the USMLE and publications in scientific journals have almost nothing to do with being "the best doctor." The USMLE is not meant to differentiate among residency candidates, though it is used for that. The best doctor communicates seamlessly with her patients. This is difficult enough when both she and the patient are speaking the same native language; the difficulty increases exponentially when non-native speakers get involved. I do not mean that to be personal in any way; it's just a fact.
But guys, you are missing the point that IMGs when they come here, they look also to advance their knowledge and practice. and I don't think they will sacrify by effort, time, and money and they don't know how to react to certain situation without language/social barrier.
Third, I am not sure the exact meaning that was meant to be conveyed in this passage, but I think it illustrates the difficulties of communicating in a non-native tongue. Add to that the subtleties of culture (both generally as well as in medicine) and you can see why programs prefer natives.
Perhaps the meaning here is that IMGs wouldn't sacrifice their time, effort, and money to train in the US if they weren't qualified vis a vis language and culture. If only the world were full of such self-aware and self-sacrificing individuals. I think IMGs want to train in the US because they can make more money, because the training is better than in their native country, and because the freedoms and standard of living that Americans enjoy is unparalleled. Otherwise, why would they leave their native countries?
One anecdote. I was working as a tour guide in a developing nation. My responsibility was principally to guide Americans and other native English-speaking tourists. Now, I speak the local language with what I think is a great degree of fluency, though certainly I am no native speaker. I probably have the same command of my second language as drmjmh9999 has of English. One day we had a tour group of locals come (which was a rather rare event) to take our tour. I volunteered to give the tour because I thought it would be fun. My boss (a local himself) disagreed because he felt it would be 'disrespectful' to force the locals to listen to a non-native guide when native ones were readily available. I was miffed about it at the time (I felt it was a personal affront at first), but after pondering the situation I realized he was right. And that was for some silly tour. How much more important is it to have doctors that you can communicate with minus any added static of language.
That is not a very very well thought out point to make. FMGs include, for example, British medical students (some of whom would argue that it's the Americans who "don't know the language enough", but that is a debate for another day) and others who do speak English as well as native speakers. Brits and other commonwealth folks also suffer from the FMG stigma. It's not just the language skills. It is a systemic bias.
Fourth, certainly not all foreign medical school graduates are the same. I am just speculating here, but I would wager that British, Australian, and Canadian entrants into the US match fare better than score- and recommendation-matched controls from the non-Anglo heritage countries. And I think that's probably because they speak native English. (Someone chime in if that sounds off base.) What's more, the medical systems between the US and other English-speaking countries are quite different. The culture is often different in subtle ways. FMGs who come to the US are probably leaving behind their families and support systems. I think all of these factors tend to favor a program taking a US grad over other native English-speaking FMGs.
I recently heard that it is the US government that pays the salaries of residents (feel free to chime in if this is either correct or incorrect). Therefore, it only makes sense to favor American-trained physicians.
Fifth, an interesting point about Gov't funding of resident education.
Finally, let's not kid ourselves. The real bottom line is that plenty of FMGs do match in the US (like 3000+ in 2009:
http://www.nrmp.org/data/resultsanddata2009.pdf).