Lack of knowledge from the person serving you has and always will be a problem, people don't stay in a job long enough these days and computer foibles are a constant issue, a computer is only as good as the operator.
I went into Bunnings a few years ago to get some 6mm nylon rope for an urgent job out on site, as the guy cut the rope he pulled out his ciggie lighter to melt the ends, he had this cocky look on his face then said, " I bet you haven't seen that before ", I said, no I'm amazed you even knew how to light it.