WalMart tends to run understaffed. One worker covering two or three departments during slow hours. Imagine a gun counter with no one around for long periods of time. I have had to have customer service call someone to the gun counter for me.
I can still remember a few years ago looking for parking at the mid-town Walmart in Anchorage; there were a group of young men all decked in "turbins' walking through the parking lot. A few minutes later they were in the store, behind the unattended gun counter, handling the guns at will without a care in the world. No employee ever bothered to attend; apparently the cameras were not attended either.