If you see that a movie is rated PG-13, what does that tell you?
If you're a parent, it may suggest to you that the film is OK for your kids, or at least your older kids. If you're a kid, it may look like a wink, telling you that, despite the approval of your parents, it's still the edgiest content you can see at the cineplex without the movie earning a restrictive R.
In other words, PG-13 is a marketing tool. What it's not: an "advance cautionary [warning] to parents, so that they can make informed decisions about which films their children see." Unfortunately, that's the exact purpose it's supposed to serve, according to the MPAA ratings board.
The ineffectuality of the PG-13 rating has become especially apparent in recent months, argues Fred Schruers at The Wrap, who cites the increasingly violent content of such recent PG-13 movies as 'Rise of the Planet of the Apes,' 'Fast Five,' and 'Harry Potter and the Deathly Hallows, Part 2.' Given such content creep, how can anyone take PG-13 seriously anymore?