> it's not necessarily legal to use information to dox if that can be construed as harassment.

This is an incorrect understanding of the issue, these individuals are protected using a unique and unusual statute. In a mass broadcast scenario, without identifying their profession in context, there's arguably no crime here. There's certainly no crime to broadcast that you've seen their license plates with no association with their names (the statute doesn't cover that.)

> Even if you crowd sourced the identification of somebody involved in a potentially criminal act, you can only share that with the police and not the wider public.

What are you talking about? This is most certainly legally false in the United States. If you are incorrect about someone you might be found against for libel, but there's no crime here. This is basic First Amendment activity. Have you never watched the news or read a newspaper? Allegations are part and parcel.

These are also entirely the wrong analogies. Both of these are highly individualized scenarios that are not akin to Flock. "Public Flock" is more like a public traffic cam that anyone can view, and these already exist without issue.