We know where you’ve been: Ars acquires 4.6M license plate scans
1. Alice installs app on smartphone.  Alice puts smartphone in cradle on dashboard.  Smartphone captures license plates Alice drives by on way to work.  Alice drives by Bob.<p>2. Carol goes to website.  Carol enters Bob's license plate number.  Website says, "25 hits found.  Enter credit card number to see times and locations".  Carol enters credit card.  Carol finds Bob.<p>3. Alice gets some of Carol's money, since she took the photos.<p>Why is that not a thing yet?  License plate reading, unlike, say, tapping undersea fiber, is not something you need either a government's resources or a government's ability to skirt the law to do.  This is easy stuff.