That's absolutely true, but it's not only a matter of translation by amateurs, or about subs that come out later, like with Blurays.
In last months, i uploaded lots of subs in most languages, and sometimes it happens that retail subs for some shows just don't come out.
It happens with several languages (with eastern europeans quite often, or ITALIAN as well), with "secondary" languages, but sometimes with most "important" languages as well, languages spoken by hundreds of millions worldwide (like ARABIC).
Few days ago, for instance, i was uploading all languages for all episodes for a brand new show and, for SLOVAK language, the official retail subs of episodes E02, E04 and one another were just missing, and probably they will never come out later.
I don't know why, but it happens.