When the US government modifies web sites to identify the people that access them, it can identify 1000 bystanders to find 100 people who are sought.

It is no coincidence that this arose in the search for people downloading illegal images. The making of those images, if it involved real sexual abuse of real children, deserves to be prosecuted, but prosecuting people for downloading something leads to tyranny.

Perhaps these images were really images of children's being abused. However, in practice "child pornography" includes 17-year-olds having sex, or 20-year-olds that look younger and are getting paid.