Which inventor created the first retail loyalty program using 'Green Stamps' that customers could collect and redeem for merchandise?

The retail landscape has been shaped by groundbreaking innovations that forever changed how we shop. Behind many familiar retail experiences are brilliant inventors who saw opportunities to enhance convenience, efficiency, or customer satisfaction. This trivia question explores a revolutionary retail innovation that transformed the shopping experience and spawned countless loyalty programs worldwide.

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Thomas Sperry, co-founder of Sperry & Hutchinson in 1896
Clarence Saunders, inventor of the self-service grocery store in 1916
Sylvan Goldman, who invented the shopping cart in 1937
Harry Cunningham, creator of the first major discount store (Kmart) in 1962