Forget Milk and Eggs: Supermarkets Are Having a Fire Sale on Data About You

Stores are happy to sell all your data to advertisers for now, but what they really want is to use it themselves. Their wet dream is to get us to accept Personalized Dynamic Pricing (https://www.researchgate.net/publication/338776528_A_special...) which means that once the store knows who you are (either by your photo, or by detecting the phone in your pocket, or by your loyalty card) they will customize the prices at the register just for you in order to take as much money from you as they think they can get away with.

They can drive up the price on the items you always buy until you stop buying as much, or lower the price on certain high price items just enough to attract you to them before they start creeping prices back up. They can use data like what you've bought from them before as well as data like your income level, who the members of your household are, and what your shopping habits elsewhere are.

Store loyalty cards are seen as a great way to start collecting useful data and get consumers used to the idea that some people get (or even deserve to get) different prices than other people. Be cautious of any place that asks you to use an app or scan a QR code to see their menu or prices, and resist the idea that stores should be allowed to discriminate by charging certain people more than others for the same product.

I wouldn't mind so much if they also gave it to me. But my grocery points card sells my shopping list to everyone else BUT me. I've looked, and PC Optimum doesn't provide line items back to the consumer.

So rude. Just like Experian and friends. Keeping detailed notes on me, and acting all surprised when I want to read them. It's like they are embarrassed I actually exist.

Sometimes it feels ridiculous how much OPSEC I need to employ to buy anything at the grocery store. I walk or bike to the store to not reveal a license plate. All radios and sensors on my handset are turned off. I wear a mask to thwart facial recognition cameras. I pay cash.

And that's why I pay cash and use Jenny's Number with the local area code for the store discount program.

I know Target also tracks your cellphone through the store too, I haven't bothered putting in airplane mode when I shop, so hopefully they aren't correlating that with the purchases.

Nothing really is done with this data, ultimately. It gets fed to 'analysts' who make models, and if those models don't agree with the decisions the executives are already making, it just gets ignored.

I’ve just always assumed that big stores were collecting and selling every iota of data they could.

I recall reading about retailers using license plate scanning in their parking lots in the early aughts.

I know Kroger (or QFC) has been doing this for ~6 or 7 years. My wife would start getting targeted ads for things that were in areas we lingered around for more than a few seconds.

FWIW Lowe's does the same exact thing. Probably IMEI harvesting but IIRC Lowe's is looking at or has implemented facial recognition. If not to identify your face outright, at least to see what you're focusing on in-store.

More reason to shop local at the hippy stores. Or start gardening.

No they aren't. I buy my food (and everything else) with cash.

When my local grocer jacked up prices and introduced a customer loyalty card to drop the prices back down to normal I found out their online system for generating the card barcodes always followed the same couple URLs. So I could just skip the customer information page, type the next URL, and get the barcode without any information in their system. Eventually I wrote a perl script to automate scraping and printing the bar codes and would use a new one every time I went shopping. Luckily the store stopped the program after a few years. I guess if human eyes looked at the data they could have figured out the "null null" customer was the same anonymous person but I doubt human eyes looked.

At my local store, the checkout clerks keep pushing me to get a loyalty card. I tried to engage once and start a conversation about privacy, but ended up walking away from the conversation feeling a little like a conspiracy theorist. But thanks to working in tech, I know this data is being tracked, bought, and sold behind the cute "loyalty" branding. I wish I knew of a good way to convince ordinary people to value their privacy, or at least not mock others who care about privacy.

This is exactly why I don't use loyalty cards. Many stores also price their goods higher than the going rate, so they can "discount" loyalty card users without actually giving them a meaningful discount. I avoid those stores entirely.

But loyalty cards aren't the only mechanism. Beware of using credit cards at stores as well, for similar reasons.

One thing I didn't see in the comments yet: at many stores in my region you can pick up a discount card and not register it, and it will still apply discounts when scanned.

Of course it won't work everywhere and it's a half measure but it's one avenue worth trying if you care about privacy to some degree but still want the discount.

We are in a new era of hacks.

We have reached the point where I can get a product removed from walmart just by buying out all of the supplies for a few months, then stop buying any.

WE knew this for years. Loyalty cards have been used to track data about you for a long time, but now they're learning how to sell it- paired with your debit card (probably backed by VISA) they can correlate and track your purchase history across multiple stores.

I just enter my ex's phone number when I check out so they see how much boxed wine she buys.

> Location: Your precise physical location in the store (with your consent), including when you enter and leave a store (Kroger app, GPS, and Bluetooth beacons inside stores)

Can someone comment on how a store can identify my Bluetooth address if I never pair with anything in the store? Do apps have access to the Bluetooth MAC? If the app is not running, can the store still identify you using Bluetooth? Is there some advertising database that contains MAC addresses tied to identities?

If you're on the store Wifi and open the app, I'm guessing the store can record the MAC address and look for it even if you're not connected but scanning.

That the two biggest supermarket chains in the US are considering merger indicates that US antitrust enforcement is far too weak.

Watching criminal interrogations, I always think if I ever get caught wrongfully, my data can be my alibi. Is this incorrect?

Here's a trick if you don't have a card/account at a grocery store:

Just put in the number of (area code) 867-5309

The number will be registered.

Always use Jenny's number 867-5309. They still link your transactions by your credit card info though.

Honestly… if we could figure out how to separate agriculture and groceries from the rest of the economy, we’d be a happier species. It’s so fucked up that the ability to feed yourself is tied to a dick measuring contest between a handful of ultra wealthy.

This is nothing compared to the Payback card in Germany. It's a loyalty program that works with a bunch of different stores and supermarkets. Currently over 600 companies.

I had no shame giving them a false name, address, and phone number for mine. I'm also aware that there are clubs that pool and swap their discount card fobs to muddy the data.

A genuine question: why does this matter for customers? Is there any foreseeable bad outcome for customers?

Well, as long as people realize their data is sold by food markets, I am personally OK with it. That said, to not get the discounts (thus not sharing your information) is leaving money on the table.

Also, if you are not part of a loyalty program, and you use a credit card, it is very possible that your purchases are still tracked - all it takes is cooperation between store and credit card company.