My answer is simple. Fear. People are just simply afraid to open the Pandora's Box of media fakery because they're not prepared to deal with the consequences of knowing that the world is not what they thought it was. When you first discover these ideas and concepts, it can be a pretty dark and sobering ride, but that's part of the journey to being awakened and set free.
Most of the population would rather remain blissfully and willfully ignorant because it's "easier" that way and they don't have to confront themselves, their beliefs, and what they hold to be true.