its not just retail store that do this. as a result of 9/11 there has been the creation of a program/service called Nexus Lexus that compiles all kinds of information on you. The program has some strict guidelines as to who can use it but its still out there gathering info on you from all kinds of sources. One thin in particular is the public records, go to whitepages.com
and type in your name and see how it associates you with other people you may live with. The Nexus Lexus program has records of just about every person in the united states, maybe more, and can trace every time your social security has been used. The primary sources going into your social are items like when you get utilities in your name. Tracking spending and purchase habits has been apart of our lives for years without our knowledge.