The problem isn't the surveillance of land; nobody is getting up in arms over someone pointing a camera out of their window to watch their neighborhood street occasionally. The problem is the scale. Flock is running a massive network of cams equipped with ML classification and segmentation algos, running 24/7, to identify and catalog plates, faces, and voices of everyone in view. It's a nation-scale realtime surveillance dragnet, and obviously not what our current legislation on public camera use was written to address.
In my area, I pass by at least five Flock cameras driving to my grocery store, meaning that Flock knows how often I get groceries, who rides along with me, which stores I visit, and how long I spend at each location. They can infer my working hours and routine travel routes. They have the technical capability to analyze the spatial and temporal distribution of my movements, and could "flag" me when I travel at odd hours or to unusual locations if they so chose. I would have no knowledge of or recourse against that invasion of my privacy.
Flock is profiting from arbitrage of the mismatch between current laws around camera use in public ("no reasonable expectation of privacy") that, when legislated, did not envision a future where cheap always-connected hardware would enable a single company to blanket the country in ML-enabled camera/microphone turrets. These aren't "just cameras in public", these are full-featured surveillance stations networked to a centralized database and powerful edge compute capability, enabling the systematic tracking of every citizen at a precision that rivals placing GPS tracking bugs on every car (which is typically illegal). And because it's a private company, none of this information is auditable by (or accountable to) the general public that is subjected to the surveillance. In my view, what Flock is doing is deeply unethical and a gross exploitation of both US citizens and the spirit of the law.