A stamp card, also called a punch card, is the simplest loyalty mechanic there is: buy nine, the tenth is free, tracked one stamp per visit. As a wallet pass, the mechanic stays the same and the paper problems go away: the card is always in the member's phone, never forgotten, never through the wash, and the stamp count updates itself.
Each visit, the member is identified the way any pass holder is, a QR or barcode scan or an NFC tap, and the new stamp lands on the pass by push update, often with a lock screen message the moment it happens. The reward state is just as visible: a full card can announce itself, and redeeming resets it without handing anything across the counter.
Digital stamps also fix the quiet failure modes of paper. Self-stamping and photocopied cards disappear, because stamps are issued by the till, not a hand stamp. And where a paper card is anonymous, a pass connects visits to a member the program can actually talk to, which turns a coffee card into a channel.
A stamp card and a points balance are the same idea at different resolutions: stamps count visits, points count spend. Stamps fit businesses where visits are the unit that matters, coffee, lunch, car washes, and many programs run both, a stamp mechanic for frequency and points for value. Getting the card into wallets is the same hosted onboarding flow as any pass: scan, join, stamp card on the phone before the first coffee is poured.