Comment by shuckles

NCMEC, not law enforcement, produces a list of embeddings of known images of child abuse. Facebook and Google run all photos uploaded to their platforms against this list. Those which match are manually reviewed and if confirmed to depict such scenes, are reported to CyberTip. If the list had a ton of false positives, you think they wouldn’t notice that their human reviewers were spending a lot of time looking at pictures of the sky?