Because Flock is privately owned while ANPR seems to my cursory research to be government owned. And we all know what private corporations do to peoples data.
I'm not sure about your exp w government agencies, but in my experience, I much prefer private companies. Much easier to hold to account.
Just as an example, NYC mayor is going after landlords for violations and tenant rights. He has hearings regularly. However there is no enforcement of the law when it comes to government owned housing projects, which are very often not kept up to code and are outright dangerously mismanaged
Yes, people pretend to not understand the difference.