The technology has changed distribution, yes. It hasn't particularly changed production, which is where the actual abuse happens. There are still actual people

The technology has changed distribution, yes. It hasn't particularly changed production, which is where the actual abuse happens. There are still actual people abusing and filming actual children, and those can be found by the police by the same old-fashioned methods they've always had available. (Plus many new ones that don't violate everyone's civil liberties or destroy the security of every networked device.)