This story reminds of one on notalwaysright.com, a site for sotries about dealing with irate customers and the like.
A cashier at a store relates to the poster that she's had several customers get out of paying by threatening her with a gun. It even has the obligatory business about "the right to be an asshole", etc. And yet, evidently, no one called the police, although it had happened repeatedly.
Oh, and of course, the poster made sure to mention their imaginary, vicarious generosity, as they told the store manager she should get that cashier a gift card or something.