[matthewdgreen]

The answer is that these databases are hugely valuable for targeted advertising and marketing, and if they’re relatively cheap to build then that makes everything even easier. Law enforcement gets access because in most countries the law allows them to make data requests to existing companies, and “we aren’t going to help the cops solve a murder” is bad PR when you’ve already collected the relevant data.

[amy214]

"let me put this vending machine in your store, you get a cut"

"let me put this camera in your store, you get $XX/month and security"

Just do that in stores in high traffic areas. Now you've got a big dataset. Overlap with location data to put a name to the face. Scifi has long seen this eg big brother eg minority reports