Apparently, they don't or they would mix it up a little. I know what you mean though. It makes you appreciate the efforts of girls like Jodie Model or True Tere or even better Princess Alla. At least they change the scenery. Now don't get me wrong, I know the real scenery is Kara's rack, but damn, isn't there a beach nearby, or a lake, or even her back yard! I looked through every set of Kara and I'll be damned if not even a single one was taken outdoors! (And in fact about a dozen or so are against a block wall in her basement.) Maybe they're just making plenty of dough without giving any thought to these deeper issues the way we do.
So message to Kara: GO OUTSIDE!
http://tightteengalleries.com/galleries5/karashan_tpb/