What characteristic defined the early machines developed by Sittman and Pitt?

They typically required the house to manually pay out winnings

The foundational coin-operated amusement devices attributed to Sittman and Pitt, based in Brooklyn, were significant mechanical precursors but were fundamentally different from the later automated slots designed by Fey due to their payout method. Specifically, these early mechanisms, often based on five-card draw poker, lacked the final, crucial step of dispensing the prize automatically. Instead, if a player achieved a winning combination, the operational requirement fell upon the house—the saloon owner or attendant—to manually pay out the corresponding winnings to the patron. This need for constant human intervention in the payment process kept them labor-intensive and distinct from the fully autonomous designs that followed.