Q. Isn't participation in supermarket "loyalty" programs voluntary?
No, these programs are not voluntary -- and it's important not to let the supermarkets get away with this semantic sleight of hand. While it is true that their monitoring programs are "not compulsory" [i.e., nobody's forcing shoppers to participate] that is different from being "voluntary." If you threaten to punish someone for failing to comply then you can't call their compliance voluntary.
Here's an example: If your employer said to you, "Your participation in some [dangerous or unpleasant] project is voluntary. It's totally up to you whether you do it or not. But you'll take a 15% pay cut if you don't." If you signed up for the project it would be hard to make the case that you did so voluntarily -- and not to avoid damage to your wallet.
The supermarket is essentially saying something similar: "We've got this nasty little data collection scheme and we want you to voluntarily sign up for it. Of course you can always say no, but you'll spend about 15% more on your groceries if you refuse."
To see just how voluntary this offer really is, ask yourself if you would still choose to be monitored if there were no punishment for refusal. If you would, then you are one of the few true volunteers and have no reason to read further. If not, then you are being coerced by threat of punishment -- in the form of higher grocery bills. Don't let anyone say you are doing this of your own free will.
"Wait a minute," I can already see the veins popping out of the necks of the market spokespeople as they read this. "You've got it all wrong! We don't punish shoppers who say 'no,' we reward loyal shoppers who say 'yes'!"
I can refute this one from my own experience. Try shopping at a market that has a "loyalty" program without a card. It won't take long to realize that you are being heavily penalized.
As for rewards, if card carriers were truly being rewarded shouldn't their grocery bills have dropped significantly since these programs went into place? As far as I can tell nobody is saying, "Wow, I save so much now over what I used to spend three years ago before my supermarket gave me this card." Instead they're gushing inanities like, "Look at how much I am saving over the 'non-club-card' price my supermarket charges people who don't sign up!"
In fact, at the bottom of many stores' receipts it may even gush for you: "Your club card membership saved you $5.40." To this I ask, "Saved $5.40 over what?"
Remember who sets those prices in the first place. There is no requirement that supermarket pricing must be fair -- that "sale prices" have to be low, or that "non-sale" prices have to be reasonable. Stores can set non-member prices as ridiculously high as they want. In fact many have done just that in an effort to squeeze the last holdouts into signing up.
If your local supermarket wants to, it can raise the price of a gallon of milk to $15 - but "reward" members with the "sale" price of $2.98. Should you then be impressed when your receipt says, "Congratulations, you saved $12.02 by using your club card"?
Rather than feel grateful for the "opportunity" to pay normal prices, you should feel angry that prices are manipulated like that in the first place. Why do they do it? Because they want to monitor your shopping.