Grocery store loyalty cards collect extensive data beyond just customer identity, including:

• Personal information such as name, mailing address, email address, phone number, and birth date.
• Detailed shopping habits: what products are purchased, how often, and in what quantities.
• Transaction data linked to payment methods, even if the card is not scanned.
• Online behavior related to views, clicks on websites and apps, and responses to advertisements.
• Device details and location data.
• Sometimes sensitive data categories like health or ethnicity, if consented.

Stores gather this data to build detailed customer profiles that allow them to:

• Tailor personalized promotions and discounts to individual preferences.
• Manage inventory and stock based on purchasing trends.
• Target advertising not only for their own products but also for third-party goods and services.
• Share data with partner companies and third-party advertisers for broader marketing reach.
• Analyze consumer behavior for research and policy-making, including public health insights.
• Increase customer loyalty and spending by offering perceived savings through dual pricing systems.

The ultimate goal is to leverage this "data treasure trove" to increase revenue through targeted marketing and improved customer retention, rather than purely rewarding loyalty

. However, this practice raises concerns about privacy, transparency, and potential misuse of data, including personalized pricing and consumer profiling

. In summary, loyalty cards enable stores to collect rich, multifaceted data on customers' identities and behaviors, which they use to optimize marketing strategies, enhance sales, and gain competitive advantage in the retail market.