Sometimes they ask me to turn my laptop on, just to see that it does actually work and is not a cleverly disguised bomb. But usually they just scan it. There's no logic behind searching my files before I board a plane to prevent terrorism. Whatever I have stored in there, if it's not a bomb, it will not explode. Are they worried that sharp words can be used to threaten the pilot?
And child pornography is even flimsier as a reason. They do know that people can send their files using a modern thing called internet, and even store them there, instead of carrying them around physically, don't they?
Anyway, if they don't specifically target teenagers to thirty-somethings, their main goal is probably not to catch copyright infringement ..