When I was in the point-of-sale software industry a decade ago, this was one of the rules of the fraud-detection system our software offered.

Employees in cahoots often "returned" unsold merchandise shortly before, or immediately after, store closing. Mainly due to legitimate customers not being present.

There were a surprising number of rules that we had developed over time, usually in response to discovery of all the various schemes that people came up with.

Buying-then-returning-within-X-minutes was another.

Minimizes the time employees are willing to spend evaluating the return.

"I really don't want to get home 30 minutes late because I was arguing with an irate customer if I reject this return."