Copyright scanning. Show us you legitimately bought and have a license to this content. Worry not if you don’t, the fines are automatic with Apple Pay.
Also on the roadmap: scanning for images of illegal firearms.
Scanning photos for images of suspects in crimes. Checking location info on photos for evidence for investigation.
Scanning texts for online bullying and sexual harassment.
Searching bank statements for tax compliance and money laundering.
Scanning for arbitrary subjects is wildly impractical. There are, what, trillions of photographs of guns in the world?