Yeah, the average counter monkey doesn't know squat.
He's paid barely over minimum wage, and rarely sees an increase in pay, even for cost of living. Corporate sees to inventing all sorts of ratings schemes to deny him that. He's not hired for his knowledge, just his or her pleasing personality, and that goes a lot further than experience. Being qualified is a detriment - if you really do know that much and can articulate it, why would you be working there?
The situation is inherently adverse to getting knowledgeable, experienced workers. I've visited my Academy, and I never see the same clerks in the department twice. Ever. How does that help establish a customer relationship? Even auto parts stores work for that - look in the back room who deals with shops and garages on a daily basis. Same guy, for years. They aren't stupid. They get the best they can and keep him.
Retail out front, no, not so much. Look hard at the corporate bottom line, you see profit, but it's NOT going to the counter guys - again, they might see a quarter a year raise, barely cost of living. They aren't planning to hang around, there's little training or incentive.
It's called retail, if you want the Low Price Guaranteed, why expect a SWAT Captain to wait on you? Not happening. There should be no illusion about that.