Why is it so hard to believe that media influence children and adolescents?

The perpetrator of the Naval Yard shooting, who killed 12 people in September 2013, spent up to 16 hours a day playing violent video games (eg, “Call of Duty”). CNN asked Dr Bushman to write an OpEd piece about the possible role of violent video games in violence. In response to that OpEd, over 1400 people made comments denying any harmful effects of violent video games. Indeed, in the US Supreme Court’s 2011 decision on video games (Brown v. Entertainment Merchants Association et al, No. 08-1448), Justice Scalia compared violent video games like “Call of Duty” to Grimm’s Fairy Tales and Homer’s Odyssey. A Super Bowl ad costs ∼$4 million for 30 seconds. Clearly, advertisers believe that a mere 30 seconds will lead consumers to buy their products. However, the media industry claims that the programming surrounding the ads has no impact on viewers. This is a paradox. How is it possible for the media to have no effect on children and adolescents when they spend an average of .7 hours/day with media (.11 hours/day if they have bedroom media) consuming it?