how do they know this?

i was just at Ralphs shopping for groceries and needed salsa. So i went up to an employee and said "wheres the salsa?" and she said without a 2nd thought, "aisle 13."

how did she know this? do they have to memorize where EVERY SINGLE ITEM is in the store? i'm always suprised when they all know this. I dont even know where i put my keys IN MY OWN HOUSE!