I think more information is stored about your personal habits if youhave a supermarket loyalty card. Every time a Tesco checkout person says
"Do you have a Club Card?"
... what they are really asking is ...
"Could our database please make a note of what you bought, and where, and when, and how often you've bought it before, and check if there's anything that you didn't buy that you do normally, and how much you spent, and which bank card you are using to pay, so that we can add to the profile we hold on you, which tells us where you are most days, and can predict your shopping habits for next month before you even write your list."
"By the way, if you would also take one of our store credit cards, then we will always know where you are every time you use it, which is particularly useful if you are abroad, or somewhere a long way from your house."
And anyone who thinks that big organisations don't do sneaky stuff might want to check out where Bob Diamond has been spending the past few days.