I get that interviewers often have anxiety about the process, but your statement isn't really true.

In a given interview, sure, he's hoping that he can hire that person, but how many people get interviewed before the position is filled? I'm certain the average is much higher than one.

No matter how much anxiety he might have, he's doesn't have to worry about stuff like paying rent, keeping his car in working order, or feeding his family, because he already has a job.