Why don't CDs have ratings?

Question

If movies and video games have ratings, why not CDs? Even CDs that don't say "Parental Advisory" or "Editted" may be innappropriate for children. In fact, there could even be pornography in the liner notes.

Answer 1

Good question, I guess because movies and video games are simulated acts of sex, violence, etc., where as CDs are just pictures in the liner notes.