That’s the trade-off the Apollo astronauts had to make. The sky on the moon is black as night not because it is night, but because there’s no atmosphere to scatter the daylight the way ours does on Earth. But make no mistake, there is every bit as much sunlight at midday on the moon as there is on our home planet. That makes the lunar surface incredibly bright.
The scenery on the moon was the most important thing to capture in the Apollo photographs, so the camera was adjusted to make the most out of that scenery. As a result, the relatively dim stars in the background didn’t register in any of the shots. No hoax, just a trick of the camera lens.