Re: There were 8600 faces detected and 7 were flagged as probable matches
We don't know how many people on the watch list of 7492 were actually among the 8600 people scanned. We don't know how many real people-of-interest it missed. Are the 8592 people it didn't flag true-negatives, or are some false-negatives? We have no assessment of false-negatives.
We only know that of 8 people it thought it found, only 1 of those was a correct match (true-positive). The rest were false-positives, innocently going about their business.
So that's a 12.5% success rate for flagged possible matches. Not an auspicious start.
They aren't sharing the false-negative rate. Probably don't even care about such things. After all, nothing to hide, nothing to fear right?
But without knowing the false-negative rate it's impossible to assess accuracy, acurately.
Hence we can only draw conclusion based on the false-positive rate, which shows piss-poor 12.5% accuracy for true-positives.
And that's the best possible interpretation. It gets worse the more false-negatives there are.