ANPR (Automatic Number Plate Recognition) is deployed on UK roads. Between 25 and 40 MILLION license plates are read every day, locating a vehicle on 270,000 miles of roads. The police retain plates for 2 years, and of course they capture every plate that passes by.
That means that 70% of journeys are recorded. Stick that data together with facial recognition .. you know where everyone has been for the last two years.
If you add mobile phone data, GPS data from Google to that, sheesh I could tell you where were with a high degree of certainty, and of course therefore who you met with, what your circle of friends looks like.
Add to that social media, IP addresses .. how on earth do we stop being devoured by the technology?
What limits its usefulness in real time is that humans can't process the data.
Scary thing is, there are no gaps now - no new technology that needs inventing. It's all here, right now.