There are no stars in the background because:
"So why aren't they [stars] in the Apollo pictures? Pretend for a moment you are an astronaut on the surface of the Moon. You want to take a picture of your fellow space traveler. The Sun is low off the horizon, since all the lunar landings were done at local morning. How do you set your camera? The lunar landscape is brightly lit by the Sun, of course, and your friend is wearing a white spacesuit also brilliantly lit by the Sun. To take a picture of a bright object with a bright background, you need to set the exposure time to be fast, and close down the aperture setting too; that's like the pupil in your eye constricting to let less light in when you walk outside on a sunny day.
So the picture you take is set for bright objects. Stars are faint objects! In the fast exposure, they simply do not have time to register on the film. It has nothing to do with the sky being black or the lack of air, it's just a matter of exposure time. If you were to go outside here on Earth on the darkest night imaginable and take a picture with the exact same camera settings the astronauts used, you won't see any stars!"
-thanks to bad astronomy.com (AND COMMON SENSE)
in other words, if you shine a flashlight in your eyes, its hard to see a little LED light across the room. period.