Movie rating systems and youth group

(source)

My roommate had some high school kids over from youth group the other night and after dinner we sat down to watch a movie in our awkwardly-elongated living room. Picking movies is always kind of a struggle with youth group kids, as you know that they've all watched NC-17 movies with their friends but you have to keep it to the PG-13 movies because you're affiliated with a church.

We decided on "Casino Royale" (which I own, I love James Bond with a burning passion) because it had the least amount of sex scenes that we could remember. However, as we were watching it, I noticed with new eyes that the movie was quite violent. Why is sex so much more of an issue than violence in movies?

While in New York City with missionary kids this past July, I was talking to a kid named Marc who grew up in Madrid. He was talking about the movie "Monster House" and how it tanked in Spain because of their rating system. Violence is rated a lot more harshly than in America, and it turned out that only 15+ year olds could get into this "kids" movie.

Assuming that we are (and I believe that we are) affected by what we see, I would assume that parents see sex as a more imminent threat to their kids than violence. AK-47s are not readily available to 15 year old upper-middle class preppy kids, while their girlfriends' bodies are. At least I think that this is the logic. However, I think that both watching sex on TV and watching violence on TV make us think of people as objects, either way. And that is nothing to be encouraged either.