So to be clear the issue isn't really about privacy at all. That is just noise. People trying to make it about privacy are liars.
The issues are:
1) A lot of people are intentionally commiting crimes of various severity and they don't actually want police to have a more effective enforcement tool
2) Some fear about false positives. Which I think is also over blown. Sure one woman was pulled from her car, and yes laziness and lack of understanding about how the system works lead to that. So sure the incident involved Flock but really policy have pulling people over or doing things like stop and frisk and getting overly aggressive for stupid reasons as long as we have had police. Flock isn't new here and really does not change anything.
The real problem is license plates at all. THAT should have never been accepted. Nobody plated up their horse or their horse cart. You can't in 2026 go around with a unique identifier being displayed or transmitted and NOT expect to be tracked everyone. You won't prevent government from collecting that data and using for things you both do and do not support. You certainly won't prevent other private parties from acquiring it and doing abusive things with it.
Flock is the symptom not the disease. People either need to demand anonymity and insist we stop displaying things like plates at all, and actually limit public photography, or just accept we will be tracked everywhere. There is no middle ground to be had.