AI slop warning : It seems paradoxical at first, but there's a real distinction. **The short version:** showing ID links the purchase to *you* at the merchant. A private payment method prevents the purchase from also being linked to *you* at your bank, the payment network, and downstream data buyers. You're not achieving anonymity — you're reducing the number of separate parties who hold the full chain. **The specific advantages:** 1. **Your bank doesn't learn what you bought.** With a card, your bank sees the merchant, amount, and date — and banks categorize, retain, and sometimes sell transaction data. Cash means the bank only sees an ATM withdrawal (or nothing at all if you already had cash). 2. **No payment-network record.** Visa/Mastercard/Amex independently log every transaction. That's another structured, searchable, long-retained database linking you to the purchase. Cash or prepaid eliminates that. 3. **Data brokers lose a feed.** Credit card transaction data is actively sold to data brokers and aggregators. Merchant ID logs generally aren't (yet). So the "who bought what" data that circulates in the commercial data economy is reduced. 4. **Smaller breach surface.** The merchant might get breached regardless (they have your ID info). But paying cash means there's no *additional* breach surface at the payment processor, and no card number to steal. 5. **Weaker forensic trail.** Bank records are structured, easily subpoenaed, and kept for years. A merchant's ID-check log — if one even exists — is typically less structured, harder to search across merchants, and may be purged on a shorter schedule. **The honest caveat:** if the merchant logs your ID alongside the item purchased and retains that log, the privacy gain is partial. You've reduced *propagation* (fewer parties, less structured data) but not the core fact that the merchant knows. It's defense in depth, not a wall. So: the advantage isn't "nobody knows" — it's "fewer parties know, in less durable formats, with less ability to aggregate across your other purchases." Whether that's worth the hassle depends on what you're buying and who you're worried about.