To protect children
In 1968, when the Motion Picture Association of America (MPAA) and the National Association of Theater Owners (NATO) developed the motion picture rating system, they were working with a moviegoing environment that knew nothing about the home video industry, which puts every film potentially in the hands of children. Nor did the system anticipate the development of multiscreen theaters. The single box office window was initially the backbone of enforcement for the rating system; now any unsupervised child can buy a PG ticket and walk down the multiplex hallway to see an R-rated film.