How do you know when the transaction is recorded as a debited wage expense account, or a credit on the cash account?

"On June 24, Costco paid wages for work performed during the preceding week in the amount of $6,700."

If I think about it, you use cash to pay employees. So, why can't you credit $6,700 to the cash account? I'm very confused about the wage expense account, so if someone could please explain that to me, that would be awesome. Thanks a lot.