> 2,470 potential matches were identified. [...]

> 2,297 - 92% - were found to be "false positives".

... so we have 173 true positives, but 450 people were arrested.

I guess the 277 wrongfully arrested ones may have an opinion different from yours.

That assumes that both numbers are for the same period and that each arrest correspond to 1 match, which most likely will not be be true. For example if system identified only subset of people, but when you make arrest you arrest all. That means that now you have more arrest attributed to system, than number of matches.

Since article does not do any attempt to answer these discrepancies, there is high chance the devil is in the details of definitions of those numbers.

You appear to be comparing two unrelated data points.

The 92% and related figures were for one specific occasion.

The 450 was total arrests since the technology was introduced.

The article specifically reports the police saying no-one has been arrested as a result of an incorrect match.

Why do you consider 170000 law abiding citizens as potential suspects? That's an extremely paranoid approach to law enforcement, especially when according to basic criminal law, these citizens are supposed to be considered innocent by default. Mass automatic surveillance of this reverses the idea of innocent until proven guilty without actually aknowleding it. That's scary