Loyalty schemes are described as rewards and are, more accurately, a data exchange with a discount attached.
What is collected
Every item purchased, when, where and at what price.
Which builds a detailed picture of a household over time.
Linked to demographic data, it supports inference well beyond shopping habits.
How retailers use it
Range decisions, store layout, promotional targeting and pricing analysis.
Which is genuinely valuable operationally and is the primary internal use.
Personalised offers are the customer-visible output.
The commercial market
Retail media businesses selling advertising and insight to suppliers.
Which has become a substantial revenue line for major retailers.
Suppliers pay for access to aggregated purchasing data and for targeted promotion.
Data protection
Frameworks in many jurisdictions require a lawful basis, transparency and rights of access and deletion.
Which means you can request what is held about you.
Subject access requests are free in most frameworks and produce revealing results.
Member pricing
Lower prices for scheme members on selected items.
Which raises the question of whether the non-member price is genuine or inflated.
Consumer authorities have examined this specifically in grocery retail.
Points economics
Redemption values are set by the scheme and can be changed.
Which means accumulated points carry devaluation risk.
Redeeming regularly rather than saving avoids it entirely.
Opting out
Using a scheme selectively, or not at all, forgoes the discount and retains the data.
Which is a legitimate choice and has a measurable cost in some retailers.
Marketing preferences can generally be adjusted separately from scheme membership.
The honest framing
The discount is real, the data is valuable, and the exchange is reasonable if you know you are making it.
Inference from purchases
Purchase patterns can indicate household composition, health circumstances and life events.
Which is more sensitive than people generally consider when scanning a card.
Retailers apply internal policies limiting targeting on sensitive inferences, with varying transparency.
App-based schemes
Location data and browsing behaviour in addition to purchase history.
Which broadens the picture considerably.
Permissions can generally be limited in device settings without losing the scheme.
Fuel and travel schemes
Points earned across partners create a broader behavioural record.
Which is the value proposition to the operator.
Partnership networks are disclosed in scheme terms.
Your rights
Access, correction, deletion and objection to certain processing exist in many data protection frameworks.
Which are exercised by writing to the operator.
Response deadlines are specified in law and are generally around a month.
The decision
Whether the discount justifies the data is a personal judgement, and making it deliberately is the point.
Personalised pricing
Different prices or offers to different members based on behaviour.
Which is legal in many jurisdictions subject to disclosure and non-discrimination rules.
Whether it is happening is difficult for an individual to detect.
Data sharing
Scheme data may be shared with partners and analytics providers.
Which is set out in privacy notices.
The scope of sharing varies enormously between schemes.
Breaches
Loyalty databases have been compromised in several incidents.
Which exposes purchase histories and contact details.
Using distinct passwords and limiting stored payment details reduces the consequences.
Closing an account
Deletion rights generally apply, subject to retention requirements for transactions.
Which means historical purchase records may be retained in anonymised form.
Requesting deletion is straightforward and operators must respond within statutory deadlines.
Getting value
Redeem promptly, use member pricing where it applies, and set marketing preferences deliberately.
The exchange, stated plainly
Detailed purchase history in return for a discount and targeted offers.
Which is a reasonable trade if you know you are making it, and most people do not consider it at all.
A middle position
Join schemes at retailers you use heavily, decline elsewhere, and adjust marketing preferences.
Which captures most of the value with less of the exposure.
A closing note
The scheme is not doing anything hidden. The terms describe the data collection, the privacy notice describes the sharing, and the discount is real. The only question is whether anyone reads any of it before scanning the card.
Fuel and household spend
Schemes covering categories beyond groceries broaden the record considerably.
Which is the point of partnership arrangements.
The combined picture is more revealing than any single retailer's data.
Children and household members
A household card records everyone's purchases under one identity.
Which is worth being aware of.
Card versus app
App-based schemes collect more than a physical card does.
Which includes location and engagement data.
Physical cards remain available in most schemes for people who prefer them.
The short version
A discount funded by data that is genuinely valuable, offered on terms that are published and rarely read.
Which makes it a reasonable exchange for anyone who knows they are making it.
Where to read more
Data protection authorities publish guidance on loyalty schemes and on subject access rights.
Which explains how to find out what is held about you.