In most cases, cell tower data is sold in the open market in aggregate. A commercial real estate developer can buy datasets that provide the average household income of passers by by hour of the day and month of the year, for example. The police can request tower ping data, generally by warrant. There are exceptions, especially in the federal space.
The Feds have a massive surveillance network. Every journey on the interstates between Miami and the border crossings near Buffalo, Watertown, Plattsburgh, Vermont and Maine all the way down to Miami is logged and tracked by a DEA program, which has likely expanded. You can get breadcrumbs of LPR hits and passenger photographs throughout the journey.
Flock is a cancer, as it is deployed by individual jurisdictions (often with Federal grants) and makes each node part of a larger network. They help solve and will likely eliminate some categories of crime. But the laws governing use are at best weak and at worse an abomination. Local cops abuse it by doing the usual dumb cop stuff -- stalking girlfriends, checking up on acquaintances. The Federal government is able to tap in to make it a node in their panopticon. Unlike government systems, stuff like user ids aren't really governed well and the abuses are mostly unauditable.
The private camera networks are a problem for commercial abuse and Federal abuse. They aren't as risky for local PDs because they generally require a paper trail to use. Corrupt/abusive cops don't like accountability.
