You can justify that, and license plate cameras for that matter, because the camera is only automating a process that the police could still have done manually although it would have taken more time and been less reliable. Namely, if a police officer is told that a person is wanted and he sees a picture of him, then he could walk around a crowd looking for people who resemble the wanted person. The camera is doing the same thing his eyes and memory does, only faster.

The problem is not so much the data collection, it's the retention. Because computers never forget, the police are then given a power the existing limits on their authority did not consider. So new laws need to be drafted to limit the actions of a police force that has infinite memory.

Which many states are doing now. Until the police unions tell a bunch of scary "think of the children" stories about why they need unlimited surveillance power. Then the issue shifts from the police to the influence of money in politics. (And perhaps also whether public employees should be allowed to unionize. Or at least, whether a union of public employees should be allowed to lobby.)

At least that is only where the police physically are.