In DL's math which calculates the breakage from their coupons and certs, a $2 refund could be approximately equivalent to the $25 voucher, which is much cheaper (simpler and easier as well as avoiding credit card fees or check fees and mailing costs) to process than a refund to a credit card or a check sent to you. I know that some businesses claimed about a decade ago that the cost of issuing a check (for a refund, reimbursement, etc.) was $35 and the cost has surely increased since then.