It's basically the TSA argument (if they are preventing terrorist attacks, tell me all about the stuff that they prevented!) Of course, none have been cited since 2001, when it was created.
The only data I could really find about Flock was from Richmond, where they went from solving 4% of vehicle thefts to 6%. Violent crime isn't discussed at all. Their sales guidance says to capitulate on the point that Flock is mass surveillance (because it is), and instead focus on reduced crime (marginal evidence) and increased crime solve rates (seems to focus entirely on non-violent crime, with modest improvements as cited above).
Like every other piece of surveillance technology, unless the benefits are world-alteringly beneficial, the system will primarily be used for abuse. Richmond scanned 22M plates (tracking everyone that drove) so they could use 100k of the scans (less than 0.5%). But the data on everyone is still being collected and sent to other parties. Flock says they retain it for 30 days, but no word on how long everyone they send it to retains it.
The opportunity for abuse is immense, and the lack of a clear claim of a massive upside is telling, despite the lack of logical continuity you're pointing out.
Flock sales pitch using Richmond data: https://pub-richmond.escribemeetings.com/filestream.ashx?Doc...