A reader of the local column "John Kelly's Washington" complains that the issuance of those little store loyalty cards has got out of hand, (a point with which I'm sure few of us would disagree) and suggests that the answer would be to develop a single card that would "do it all," register our purchases in every place we went.
In fact, this technology already exists, so it may not be so difficult to achieve, if we really want it.
Do we? As Kelly points out, the real purpose of the cards is to gather information about your buying habits, your favorite brands, the frequency of your purchases, and such, so that they can sell to you more successfully. Many consider this an invasion of privacy, and might find the combination of such data from many stores on one card even worse, regardless of whether the data is controlled by different chips and supposedly remains compartmented. (I predict it wouldn't; if individual stores couldn't access it all, the makers of the cards and the card readers certainly could.)
I'm not much concerned about privacy in this situation, but I do think it's essentially unfair for retailers to use the cards to discriminate against those who don't have them. In most stores with such cards, you don't get the "sale" price unless you have a card. Yet stores still publish those big ads, touting those low prices on milk, toilet paper, or ice cream; and those ads are intended to draw in all customers, not only those who already regularly shop at that outlet. In fact, I'd argue the sale ads are more aimed at drawing in a new customer than an old one.
With that in mind, it seems about the only way around the proliferation of these annoying cards is grass-roots revolt. Check out without the card; go to the store manager afterward to complain about not getting the discount; and if he/she isn't prepared to rebate, insist on a full refund of your purchase, and go to another store. A manager who has to deal with 100 or more people a day this way is going to realize very quickly that he can't afford the time; he'll find a better way. If there's a sale price, everyone should get it.