Which retail innovation was FIRST widely implemented in military exchanges (PX/BX) before becoming standard in civilian retail?

The Post Exchange (PX) and Base Exchange (BX) systems represent one of the most unique retail networks in American history. These military department stores have evolved from frontier trading posts to billion-dollar retail operations that serve military communities worldwide. This poll tests your knowledge about this distinctive retail system that has been an integral part of military life and has pioneered several retail innovations before they reached civilian markets.

This is a live public trivia poll on AIPolls.Net. Vote and see real-time results.

Universal Product Code (UPC) scanning systems
The use of debit cards for purchases
Self-checkout kiosks
Loyalty rewards programs