Honestly, the music industry is way better than the movie industry. The MPAA rating system is a literal censorship board, complete with an actual member of the clergy serving in an advisory role on all appeals. But if you don't get your film rated, it's almost impossible to distribute it to anyone but the very small independent movie theaters.
The MPAA results in an immensely chilling effect, which influences the movies people produce in the first place.
Contrast that with music, where the distribution mechanisms are much more varied than for film, and there's nothing preventing people from releasing music with incredibly explicit lyrics, as long as they don't expect the uncensored versions to be played on the radio - a medium which, while still popular, is by no means thr primary distribution channel anymore.
If you believe that, I recommend you watch This Movie Is Not Yet Rated[0].
It's just as bad in movies :-). I don't know anything about game ratings to dispute that part, though.
One problem is that the interpretation of lyrics is subjective, as this FBI investigation so well illustrates. Albums that sound sufficiently pop/clean/bubblegum go without the sticker when there are clearly songs explicitly about sex/drugs/etc.
For an example, look at Third Eye Blind's self-titled, debut album. Semi-Charmed Life is clearly about meth and sex, but it is sufficiently clean sounding that it gets by without a sticker.
Meanwhile, albums that sounds a little edgier, but are actually about clean, mundane subject matter have the sticker forced upon them.
IMO, the movies and games industries have much better, more objective rating systems.