text: I've never been to college, didn't even finish high school, but I can tell you it is Personal Bias, Political Bias, Commercial (or money inspired) Bias.   \n\nThe media outlets all must have a positive profit model in order to stay in operation, this means there is quite a bit of external influence as to what is reported and what is left out, and this influence even extends to how the information which they do report is worded. \n\nIgnorance is a factor that plagues the internet and some news outlets.  It's difficult to know what factors could be influencing an anonymous person to make claims.  Their health, their experiences,  their likes and dislikes, what they intend to achieve with the claim, all have influence.\n\nProduct manufacturers, or any publicly traded company can be held financially liable if they don't do everything within the law to garner the greatest margins of profit for their business.  This encourages advertisement to be rife with misleading images, words and even subliminally suggested intentions.   Money is a huge factor that influences all advertisement claims. \n\nI have to note that each of the fields you mentioned have their own specific influencing factors, and it's difficult to generalize them across the whole lot.  For instance, a movie's claims are often motivated by the writer or directors specific intentions of how they wish to influence people with the work.  You aren't likely to see this as much in say.. news reporting.