As an example, see the recent case of the woman who was arrested simply for driving through a town at the same time as a robbery occurred. That sort of thing is why people care.
If the data collection is performed by a private entity and then sold to the government, that is government surveillance. I agree that this is more widespread than Flock and other big names. However, Flock and its ilk currently stand to do far more damage in practice. They offer integrated turnkey solutions that are available to practically any law enforcement, from shithead chud officers in tiny shithole towns to the NYPD and all its grand history of institutionalized misconduct, and we are already seeing the effects of that.
See, also, the recent case of a teenager who was arrested because a Flock camera or similar thought a Doritos bag in his pocket was a gun. I'll let you guess what color his skin was.