Comment by the_other

If a phone calls the API "hello, I found some porn here" the phone (and/or it's owner) become a "person of interest" very quickly.

(I'll wager) The majority of these calls will be false positives. Now a load of resources get deployed to keep an eye on the device's owner, wasting staff time and compute, wasting (tax funded) government budget that could have gone towards proper investigation.