The New York Times' movie critic A.O. Scott gets the ratings system better than almost anyone in the media.
Mr. Dick’s film, a critique of the ratings system in the name of artistic freedom, dwells on the commercially fraught boundary between the R and NC-17 ratings, which caused problems for the directors of films like “The Cooler,” “Boys Don’t Cry” and “A Dirty Shame.” But for the public — at least for children and their parents — the more embattled frontier is the one between PG-13 and R.
In actual ticket-buying practice, the difference between them is that a young-looking adolescent must be accompanied either by a full-fledged adult or by an older-looking adolescent. Otherwise it may take a practiced eye and ear to realize that a popular Anglo-Saxon expletive is acceptable in a PG-13 movie as long as it is only heard once and does not refer to a sexual act. Thus “Billy Elliott,” as wholesome and uplifting a film as you could hope for — its story about a kid who dreams of being a dancer is likely to inspire other kids with similar dreams — has an R rating because its proletarian English characters talk more or less as they would in the real world.
It is easy to scoff at that rating only if you have never received angry letters from parents or grandparents appalled by profanity. But of course the rules about specific rules allow a lot of leeway, and no one would claim that by taking your children only to PG-13 comedies, say, you would spare them sustained exposure to coarse sexual humor. Nor would a PG-13-only diet prevent them from seeing violent deaths and grisly images, including the genocidal warfare in “Avatar” itself.
Read the whole thing. It's really good.