Here is my unsolicited opinion on programs with IMGs and maybe (only by extension) D.O.s. There are many diamonds in the rough among IMG applicants. There are well established UK modeled excellent schools throughout the subcontinent that turn out excellent doctors. The problem is that there are some well-oiled medical mills that do not meet these standards, and it is very hard to tell the difference. The best students at the worst US medical school will always shine. The worst student from the best US medical schools will always disappoint. The core of the bias is that domestic medical students put stock in the % of IMGs and/or D.O. trainees, so even the most open minded programs learn to pay attention to this. Programs that have had wonderful experiences with IMGs cannot survive limiting their access to US grads.
If you are an IMG who rails against the prejudice you experience among US program directors, refer to open market dynamics for some understanding. Even if you kidnapped all program directors and subjected them to intense destigmatization training, a couple of recruitment cycles would have them revert back to the current state of affairs unless the bias that exists among the their customers is addressed.
What feeds this bias is an interesting question. We had an IMG in my program and he/she was terrific. Would you consider training with all IMGs? Oh, of course not. Just going into psychiatry requires some capacity to not care what others think, but somehow this has created some sort of reaction formation when it comes to medical school snootiness.