Why do dark skinned people don't get skin cancer?

Dark skinned people get skin cancer just like white people do. That is completely incorrect.

Who Gets Skin Cancer?
Skin cancer develops in people of all colors, from the palest to the darkest. However, skin cancer is most likely to occur in those who have fair skin, light-colored eyes, blonde or red hair, a tendency to burn or freckle when exposed to the sun, and a history of sun exposure. Anyone with a family history of skin cancer also has an increased risk of developing skin cancer. In dark-skinned individuals, melanoma most often develops on non-sun-exposed areas, such as the foot, underneath nails, and on the mucous membranes of the mouth, nasal passages, or genitals. Those with fair skin also can have melanoma develop in these areas.melanin protects their skin.
They do, just less often. The increased melanin helps to absorb the damaging portion of solar radiation wihtout ill effect.
They do but since the skin is darker it means they produce more melatonin (spelled right?) in their skin and don't get burned by the sun as easily as light skinned people, therefore the risk of skin cancer goes down.
Melanin is a skin pigment that both makes the skin darker and blocks out harmful UV radiation. Black skin blocks out about twice as much UV as white skin does. It is rarer for dark skinned people to get skin cancer, but it is just as deadly.
Because people with dark colored skin have more melon in their skin, which is the body's natural sun block, the melon protects the person from harmful uv rays that cause skin cancer.