Foreign born MDs get an automatic Green Card - no quota!
Might be true for Dentists, too, but I have not confirmed that.
Yes, without the foreign doctors American seniors would be deprived of medical care. There is a shortage of doctors especially specialists. It takes decades before a doctor earns good money. And he/she is on call 24/7. My daughter quit medical school, because she did not wish to sacrifice family life. Now she id doing clinical trials for new cancer drugs, a 9 to 5 job and is very happy.