GP made it sound like the cashier is already watching this happen, but yes, I've been the one walking around and observing customers for my Grandmother's estate

GP made it sound like the cashier is already watching this happen, but yes, I've been the one walking around and observing customers for my Grandmother's estate sale business, but that's because it was helping my grandmother out; I doubt you'll find many people willing to do that for minimum wage. And I also doubt many store owners want to pay the wage and health insurance costs for an employee to hang out and observe/chat with customers. I doubt any even fractionally-rational human goes into a store willing to kill for food, but shit can go sideways instantly when you start engaging in physical confrontations, particularly in a country where firearms are trivially obtained and carried; it's a latent threat in nearly any situation in the US.