4 pieces of data is needed to identify one based on his electronic shopping habits:
http://www.sciencemag.org/content/347/6221/536.full
And then there is what the stores are doing:
http://www.wsj.com/articles/startups-see-your-face-unmask-your-emotions-1422472398
and
http://www.wsj.com/articles/SB10000872396390444897304578044322254166986
And finally DEA Is collecting license plate data
http://www.wsj.com/articles/u-s-spies-on-millions-of-cars-1422314779