Devil's advocate: It may not be mostly big organized crime.
It may be hard to fight, because it's not groups. It mostly comes from people close to the families, or the families themselves.
Here's a relevant extract sourced from Wikipedia:
"Most sexual abuse offenders are acquainted with their victims; approximately 30% are relatives of the child, most often brothers, sisters, fathers, mothers, uncles or cousins; around 60% are other acquaintances such as friends of the family, babysitters, or neighbours; strangers are the offenders in approximately 10% of child sexual abuse cases.[53] In over one-third of cases, the perpetrator is also a minor.[56]"
Content warning: The WP article contains pictures of abused children.
Sure, but the people sharing these images do so in organized groups, often referred to as "rings". I agree it would be very hard to catch a solitary perpetrator abusing children and not sharing the images. However since they would be creating novel images with new hashes, Apple's system wouldn't do much to help catch them would it?
Here's a relevant extract sourced from Wikipedia:
"Most sexual abuse offenders are acquainted with their victims; approximately 30% are relatives of the child, most often brothers, sisters, fathers, mothers, uncles or cousins; around 60% are other acquaintances such as friends of the family, babysitters, or neighbours; strangers are the offenders in approximately 10% of child sexual abuse cases.[53] In over one-third of cases, the perpetrator is also a minor.[56]"
Content warning: The WP article contains pictures of abused children.