Ehh, it's just another part of education, let some people pay their own way. However, that requires fewer years upfront so the costs are more reasonable.
Pay their own way? Residents are already in 8 years of debt after undergrad and medical school education. How could you expect a person to keep paying their way for a total of up to 13 years of education (what it takes minimum to become a surgeon after high school in the US)?
You don't get it. The government limits the amount of residency spots. They fund the residency spots. And most students do not pay upfront, they go into debt to fund their education. Having students pay more or go more into debt will do nothing. The amount of residency spots is ultimately determined by the US govt