They can find paedo's they just can't or won't do anything about them as they are entrenched in society.
As others have said. How exactly? Stop one and 10 more pop up.
Or more accurately than that - they can find mass producers of child pornography who are the heads of rape gangs all over the world but they refused to tell a judge how they proved it was them so let them all walk free. This actually happened and I'm still angry about it