Many news orginizations have bias because of political payoffs or opinionated leaders. It is often forgotten thats news reporters are also average people, directing attention to different societal issues does not rid them of their own opinions. Also political leaders may often times be in cohesive alliances with certain news stations, making their information now skewed in support of their allies. New information could also be gained from the public or social media which in turn becomes a game of telephone for society making it easy for stories to get switched or information to be lost.
