A completely eye-opening article:
"Yet companies continue to claim that the data are anonymous. In marketing materials and at trade conferences, anonymity is a major selling point — key to allaying concerns over such invasive monitoring.
To evaluate the companies’ claims, we turned most of our attention to identifying people in positions of power. With the help of publicly available information, like home addresses, we easily identified and then tracked scores of notables. We followed military officials with security clearances as they drove home at night. We tracked law enforcement officers as they took their kids to school. We watched high-powered lawyers (and their guests) as they traveled from private jets to vacation properties. We did not name any of the people we identified without their permission."