My shirts aren't private???

In the Gertner article, I found it sickly fascinating how much information there actually is out in the world about each individual. I assumed that there was some info out there about certain aspects of our lives, but the fact that information can be tracked down to what stores we buy shirts from and have that tagged into a political campaign for one candidate or another! I thought this was insane. Obviously there are stereotypes that go along with which political party you side with, but I never realized that politicians would go down to the nitty gritty details of our lives to try and decipher what party we should be affiliated with so that they can target us. This invasion of privacy I find to be ridiculous to a degree. What if I just simply like shopping at J Crew? What's the difference in my mind about the clothing they sell rather than the fact that I'm getting clothes there to "be true" to a political preference? Is there a line that the government has to decipher what the different demographics can lead to? Is that extra invasion of privacy necessary for their win in an election? (How much do you feel it actually helps?)