Which retail innovation was first widely implemented in military Post Exchange (PX) stores in the 1950s, decades before becoming standard in civilian retail?

Post Exchange (PX) stores have been a cornerstone of military life for generations, providing essential goods and services to service members and their families worldwide. These retail operations have evolved significantly over time, adapting innovative practices that later influenced civilian retail. Test your knowledge about a groundbreaking retail innovation that originated in military exchanges before becoming standard in civilian stores.

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Self-checkout kiosks
Universal Product Code (UPC) barcode scanning
Fixed pricing (no haggling) with clearly marked prices
Loyalty card programs