True story-

A few years ago at airline X, flight ops management started requesting doctors notes for every sick call.

So pilot xxx calls in sick due to a headache. Nothing serious, just an average, run of the mill headache. The next day he calls in to try and rejoin his trip (as he was allowed to per contract) only to be told the company wanted a doctors note prior to being allowed back on. So he heads to a local airline appointed clinic and reports to the doctor that he needed the note to go back to work. The doctor, angry that the company is wasting her time with mundane appointments, orders over $20,000 in tests to ensure the headache was not caused by something more serious.

Eventually the company gets the bill and tries to pin the cost on the pilot, calling the testing excessive and noting he should have refused the testing. His argument, which eventually stands up, is the company sent him to the doctor on their bill, the pilot has no medical training and thus was not in a position to question the judgment of the doctor when requesting the tests.

Airline x takes a very long break from requiring doctors notes for sick calls.