You think USA government agencies never thought of using public surveillance cameras to spy on people before now?

No. I do not.

I think allowing a private company access to that kind of data, without any meaningful restrictions on what they can do with it, is a lot different than the current situation of 'spy agencies can spy for the government'.

If I'm a bad guy and I can get access to a Flock (or Palantir, fed by Flock) subscription then I can do bad guy things a lot more effectively. Can you think of any bad guys who could afford such a subscription?

Who owns that data and what rules it falls under is important. The government needs a warrant to obtain cell-site location tracking data, but Flock can sell a subscription to obtain that same data to anybody who can clear an ACH transfer.