A long time ago I had a brief e-mail exchange with a nurse somewhere in a hospital on the east coast. The subject was flu shots. Here is what she said:
All hospital employees were required to get flu shots.
But there was one exception:
NO DOCTORS ELECTED TO GET FLU SHOTS and they were not required to do so.
Easy answer: the sawbones are not employees, they have “admit privileges” or “surgery privileges”. If the hospital tried to get them do something the docs don’t want to do, the docs just go somewhere else with their patients and the hospital loses out entirely.