Then the candidate had a relapse. If you've got the flu, you probably look terrible, feel worse and can hardly think straight. But many candidates don't. They fear they'll be out of the loop unless they crawl in. Or that the hiring manager will think they're flaky if they cancel.
Some professionals feel as though they're slackers if they postpone an interview.
Something from childhood and missing school seems to kick in and they feel guilty about being sick. Their fevered brains aren't functioning properly. Calif. He's had to set up new interviews with candidates who had shown up sick for their first meetings because managers couldn't tell if they were right for the job. This doubles the work for candidates, recruiters and managers. A candidate might as well spend the extra hour sleeping.