I don't buy the argument that parents are helpless against marketing. If you don't want your kids to see certain kinds of movies, don't let them. Take a stand. Even if they nag. Caving in to an advertising campaign, then blaming Hollywood, is a cop-out.
Deception is about misleading consumers to their detriment.
Deception is about causing some injury that is not reasonably avoidable. But we're talking about rating classifications that are guidelines, with no legal weight. They are voluntary industry standards. To regulate a marketing effort based on voluntary guidelines raises troublesome First Amendment issues. Even studio executives agree there have been some abuses.