I think your critique of police here is orthogonal to the privacy discussion, which affects everyone:
Imagine the danger and legitimate fear a stalking victim would face if there was a public real-time tracker for any license plate query you can imagine.
What if there was a book that listed everyone's phone numbers?
What if it also listed everyone's address and their full history of travel on all roads, ever, with a queryable interface?
So, like, cops are currently doing?
Imagine the danger and legitimate fear a stalking victim would face if their stalker is a police officer with access to Flock.
A lot of this boils down to ‘we have bad police’.
I am no fan of Flock but there is more than one problem here.
A few rotten apples do spoil the whole bunch.