I am sure that for every person who did not make it, there is another one who manages to get licensed. I peronally met plenty of doctors who were trained in a foreign medical country, now I am not talking countries that have never heared of USMLEs, can still manage to pass the necessary tests and get the license to practice medicine. The important thing is that medicine is exactly the same in every coutry and passing a standardize exam depends completely on the individual.