Which retail technology was first widely implemented in U.S. military exchanges before becoming standard in civilian retail stores?

Post Exchange (PX) and Base Exchange (BX) stores have been vital to military morale since their inception. These military retail operations have evolved dramatically with technology and consumer trends over the decades. While serving military personnel and their families, these specialized retailers have pioneered retail innovations that later spread to civilian markets. Test your knowledge about the interesting intersection of military retail operations and technology!

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Universal Product Code (UPC) barcode scanning systems
Self-checkout kiosks
RFID inventory tracking
Facial recognition payment systems