Next time you are in one of these type of stores, take a look around at all the employees. Imagine making policies that would be appropriate for all of them. That's where policies come from. I don't care for "zero tolerance" policies, but they are probably the best idea for large number of unequal skill employees. The last thing you want is for every employee to start making up their own actions for any potential situation. Firing may be too harsh, but the penalty must be the same for everyone.