> even if the scanner is 99.99% accurate, because an even higher percentage of photos are innocent, most matches the scanner will find will be false positives.
If the scanner is 99.99% accurate, then most classifications will be correct.
If the scanner is 99.99% accurate, then most classifications will be correct.
So a quota of 0.1% or even less material being detectably criminal sounds realistic (probably not much less, though).