Which retail technology innovation was first widely adopted by military exchanges (PX/BX) in the 1970s, decades before becoming standard in civilian retail?

Military exchanges (PX/BX) have evolved significantly over the decades, transforming from basic supply stores to sophisticated retail operations serving military personnel worldwide. These unique retail environments blend commercial retail practices with military logistics and have pioneered several retail innovations. This trivia question explores an interesting technological advancement first widely implemented in military retail before becoming mainstream in civilian markets.

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Barcode scanning inventory systems
Self-checkout kiosks
Electronic payment cards
Computerized supply chain management