This is something I never understood. With a book, you can't focus on background things, as it'd distract from the story, leaving readers to be jarred. However with a movie, you see things, just simple things in the background, you probably won't notice them until you've watched it several more times. Like for example, when Luke first arrives in Mos Eisley, can you imagine a book going to length to describe what was going on? No, it's ridiculous as it'd distract from the plot too much, if it does distract like that, then it's a **** book.
However, in the movie, you see it all, all these things going on, yet the story still happens, yet for that brief second, you glimpsed the magical things that are placed everywhere. Subtle, simple, yet there. Movies > Books for things like that. You can't subtle describe a scene completely in a book, hence why descriptions are brief and vague when it comes to books, unless it's describing something that is either small, simple or easily describable.
It's really interesting to see a new generation (and I'm not even that old) of people consider that books (pictureless ones anyway) are somehow a lower art form than film. The setting and background of book story is not limited by lack of visuals. It is limited by a lack of imagination.