Even retail establishments with staff and security systems balance the extra costs of these “loss prevention” measures against customer convenience. The goal is never perfect security but sufficient security. Large retailers typically set targets on loss and try to minimize them, within reason. Farm stands that operate like this have simply found a reasonable cost/benefit trade off. (There’s an apple orchard near Boston that leaves their store unattended for the slow winter months... My wife pops in a few times to buy some more apples.)
Loss from stealing was called 'shrinkage' by retail industry people, in Sam Walton's autobiography 'Made in America'. As you say, they expected to have some. I wonder why it can't be prevented 100%.
Prevention to 100% would be costly. They have diminishing marginal returns.
Why would someone pay $50,000/year for a hypothetical system which would theoretically catch everyone and fill out the police report automatically when the store experiences a tiny $300 annual shrinkage loss?
Lying for Money makes the case that the optimal amount of fraud in any real world system is non-zero. Fraud prevention has direct and indirect costs. At some point the costs of fraud prevention will exceed the cost of fraud itself.
