EAN-8 is the short form of the EAN retail barcode: eight digits including a check digit, in a symbol narrow enough for packaging that cannot carry a full EAN-13. Confectionery, cosmetics and small tins are its typical home.
Numbers are allocated centrally rather than derived from a company prefix, precisely because there is not enough room to encode one. That scarcity is why EAN-8 is reserved for products that genuinely need it rather than used by default.
In a loyalty context it appears where a short member number was chosen deliberately, often for legibility or for keying in manually when a scan fails. Eight digits are easy to read aloud and quick to type, which is a real operational advantage at a counter.
Google Wallet renders EAN-8 on passes. Apple Wallet's formats are QR, PDF417, Aztec and Code 128, so an Apple pass carries the same digits as Code 128 or a QR code. See QR and barcode identification.