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

Military exchanges (PX/BX) have been vital retail institutions serving military personnel for centuries, evolving from simple sutlers' wagons to modern retail complexes. These specialized retail operations have pioneered many innovations in merchandising, mobile commerce, and omnichannel strategies to serve military families worldwide. This trivia question explores a significant retail technology advancement that originated in military exchanges before becoming mainstream in civilian retail.

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Barcode scanning and computerized inventory management
Self-checkout kiosks
Online ordering with in-store pickup
Contactless payment systems