how does subtitling work?

I mean, like, who does that, and what kind of resources or training do they have? Who pays for it? Who does quality control?

I usually watch movies with subtitles on, even though I hear well enough to understand most movies when subtitles aren't available. Turning sounds into words is work. Work I'm happy to let someone else do for me. But sometimes the subtitles make the movie less comprehensible, like in Little Fish, which is Australian:

Hugo's dealer says, "There'll be no more packages. At least not from me."
The subtitle reads, "The enamel packages. This is not for me."