They trust you.
You’ll be more likely to buy again, knowing they won’t give you a hassle.
Most merchants make you wait until you send back the broken product before they ship the replacement — leaving you with nothing for several weeks. Making you feel like you did something wrong. Even when the defect is their fault.
Amazon does have your credit card in case you don’t send back the return, but so do the merchants who make you wait.
Who are you going to buy from next time?
Are you showing your customers that you trust them?