Why do we say “in” a movie but “on” a TV show?

When referring to a television program, my experience tells me that it is proper to use “on” whether I’m referring to an actor on the show or events on the show or anything.

Did you see Matt Damon on Saturday Night Live? The sketches on that show are funny.

With films, on the other hand, I always hear people using “in” for the same purposes.

Did you see Matt Damon in Good Will Hunting? The scenes in that film are powerful.

It could just be a trend that caught on in either case, but I’d love to know if there’s a definite explanation for this use of these prepositions or if there has been any scholarly work on the topic.

Solution 1:

My guess is that before movies and TVs people acted in plays, on a stage. Plays became movies and the TV became a sort of small personal stage we have in our houses. We turn it on with a switch, and while it's running we refer to it as being on. It seems to follow naturally that we would say "What's on TV tonight?" "Saturday Night Live is on."

On the other hand, characters and scenes are in plays and movies the same as they are in a book. A book or a film is a closed entity that contains things, so things are in it.

Solution 2:

Perhaps this is because TV shows are ongoing, and movies aren't. Movies were made once and that's it, while a TV show is continuously being produced.

This seems to be similar to how you would refer to being in a train. If the train is moving, you are on the train. If the train is stationary, you are in a train.

Just a thought.