Why is the government able to control broadcast media more easily than print media?

Salman Rushdie might have given one of the best examples of why censorship is needed to keep peace in a totalitarian state when he said, "Free societies...are societies in motion, and with motion comes tension, dissent, friction. Free people strike sparks, and those sparks are the best evidence of freedom's existence." By controlling the media you can control, to some extent, the zeitgeist in a community.