Why does rubbing a coin on steel make vending machines accept it?

A 3D render of a closeup of a coin slot panel from a vintage arcade game machine with entry and exit slots and perspex button on an isolated background

Our vending machine accepts credit cards by tap or swipe It also accepts bills in a place that is clearly marked and says accepts $5, $10, $20

vending machine slot demo Vending machine coin acceptancerejection systems Any static charge would be immediately removed when the coin touches the metal slot

vending machine slot slot machine was an offense under the statute irrespective of whether it was money or other valuable thing is staked or hazarded by placing or