Politicians know that information is power and information is what drives our actions. So the easiest way to get the masses to act in a particular way is to feed them information that corresponds to that. I assume many of these dirty power players take control of the media through bribery or threats, much like Pablo Escobar's silver or lead principle. It will take a long long time to bring truth back to mainstream media and an even longer time to restore the corroded trust of the masses.