I wildly guess that you may find long-standing relationships between those popular creators and the caption writers, such that they've built some measure of tru

I wildly guess that you may find long-standing relationships between those popular creators and the caption writers, such that they've built some measure of trust. Captions contributed by a new author might get vetted more closely, e.g. at least run through an online translator to see whether it's plainly wrong / torrent of insults / etc.