Foreign trained doctors

Why does our country and medical system allow foreign trained doctors to practice and do residency in the US? I understand that the more doctors the better the health-care and competition is good; but, I have already rotated with 2 doctors who did medical school in Europe FOR FREE....so they literally get their "degree" and come into the country and start making the same revenues and income without the debt/investment compared to US trained (who likely starts with $200k debt). See this with... Foreign trained doctors
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums