Like I said - more power to you if that's what you want to do. However, your extremely defensive response suggests simple denial rather than an educated evaluation of the risk-reward trade-off.
And for the record - I don't use grocery loyalty cards, I only shop at stores that don't have loyalty card programs. Not only are they a prime example of a poor trade off between a significant amount of privacy for a handful of dollars, they are actually a false economy. See this article for an explanation: http://www.nocards.org/savings/regul...ce_study.shtml
Of course I have something to worry about - increased privacy means increased safety and security. Your suggestion that "you have nothing to fear if you have nothing to hide" is naive at best. Privacy isn't about hiding bad things, its about not making it easy for people to hurt you. You might as well argue that the only reason to hang curtains in your windows or use sealed envelopes instead of postcards is to hide criminal activity, or that only bad drivers need to wear seatbelts. Only a fool would believe those things because after decades, even centuries, of experiences the risks have been made obvious to even the most incurious - information security is just in it's infancy so most people haven't really given it much thought. My point in responding to you is to say - hey maybe you should think about this a little bit more than you have been.
If they pay you they have enough information to connect the dots and if you think they don't do everything they possibly can to connect those dots, you just haven't been paying attention. Here's a good place to start to understand the mentality of the people you are dealing with - at that bastion of tinfoil paranoia the wall street journal: http://online.wsj.com/article/SB1000...512989404.html
No you can't. I practice what I preach. Try googling me if you don't believe me.
I will give away a couple of dots - I spend a lot of time thinking about information security because it's my job. I was one of the engineers that built the current IAFIS in Clarksburg and I regularly consult on information security to a few large organizations you've probably heard of, from the sound of it one of them may even employ you. I'm probably the only VX owner to ever work IAFIS so, in the right hands, that information is enough to identify me. I choose to reveal it because I believe the trade-off of dispelling the accusations of tinfoil-hattery to be worth the unlikely chance that anyone reading this is able to cross reference that group of engineers with the group of VX owners. More practicing what I preach about risk-reward trade-offs.
And, while I'm at it, here is a interesting essay on how just three pieces of information - gender, zip code and birth date is enough to uniquely identify almost 90% of the US population and how that can (and has) lead to unexpected disclosures of personal information: https://www.eff.org/deeplinks/2010/0...ry-and-privacy.