just like every other cultures there are many differences between film.
In france> everyonetypically dies in their horror/drama movies
In germany> its not uncommon to have a s'e'xn sceen in the movie that is unedited.
And pleanty of other examples. I do not remember the country but in one of them women are never the main character. Something that is common by our standards and uncommon by other countries is that we barely have nudity. Plus in most movies in america their is a happy ending.
So this is just one of the many trends that come with different cultures, though I do only think america shares this one to themselves. Thats why I like foreign films because the happy ending and the stupid stuff over and over again, i mean we all can go to any moie now and pick the main character out in like the first 20 min of the movie, and then tell everyone that will die and how the movie ends.