[ThinkingGuy]

I lived in Japan in the 90s and watched a LOT of TV there. From my experience most subtitling on TV fell into 2 categories:

On anime and children's shows, the theme songs were frequently subtitled. I assumed this was so viewers could appreciate the lyrics

Comedy, skit and variety shows, where the dialog and commentary is mostly banter amongst a cast of "wacky" hosts. Here, subtitles (almost always in a garish, colorful font) served to punctuate jokes or funny lines, in the same way that a laugh track on an American sitcom is used to let the audience know when to laugh (even though the Japanese shows usually had a laughing studio audience as well).

Some shows did (do?) go overboard with the "comedic" subtitles, to a point where they were subtitling almost every other line a host said.