When was the last time you saw a short film in the theater? I don't mean an 85-minute animated movie; I mean an actual short, like they give separate Oscars to. Otherwise known as a short subject, defined (by the Academy) as anything with a running time less than 40 minutes. Chances are, unless you attend film festivals, go to see the toured screenings of Oscar shorts, or bought a ticket to Paris, Je T'Aime, it's been awhile since you actually saw a short film on a big screen.
Or, maybe I should specify that it's likely been awhile since you purposefully went to see a specifically timed screening of a short film or compilation of shorts at the theater. Technically some ads for Coca-Cola and other companies, the ones made by novice filmmakers as part of a competition or something, count as shorts. And, I'm fully aware that some arthouse cinemas, such as NYC's IFC Center, run a short film in place of pre-show commercials. But as far as I can tell, such shorts are not specifically advertised as screening at a designated time. Sure, you can go on the IFC Center's website and find out that Erik Rosenlund's Looking Glass is the short currently being shown (as it was this past week when I saw Trouble the Water there), but for most people (myself included), it's a surprise. And I doubt anyone has trekked to IFC just to see that particular film, unless anyone is a huge aficionado of frightening black and white Swedish animation.