Yeah, residency programs are extremely expensive to run -- most of the work they do is duplicative, especially for 1st & 2nd year students. You're essentially paying multiple doctors a little money to follow doctors who make a lot of money around. They do cover overnight shifts, but they still need to be supervised by 'real' physicians so there aren't really any savings. Vox did a good summary of the whole situation last year;
I would say it's not so clear, and it's open for debate until hospitals open up their books.
Yes residents need to be supervised, but one doctor can supervise many residents seeing many more patients than they could alone. If hospitals didn't have residents they would have to hire more doctors.
Also consider that a resident costs less to employ than a nurse and that the hospital bills for all the work residents do.
Finally, doctors in teaching hospitals tend to be payed less than doctors in non-teaching hospitals.
https://www.vox.com/22989930/residency-match-physician-docto...