I’m pretty sure Jack Benny used the elevator joke at some time in his radio or TV career. Maybe others like the Marx brothers, the Three stooges or Abbott and Costello. It was probably used a lot from vaudeville comedy.
Blame white men for developing comedy.
Back in the radio days of Jack Benny, the elevator operator was usually voiced by Mel Blanc. It’s the voice I hear in my head when reading these posts by those unaware of the cultural background of the professor’s comment.