Originally Posted by
sethb
Whenever I've gotten a voucher, it replaced cash spending. So a $300 voucher cost Delta $300 in revenue (less credit card fees).
I think the point is that the voucher isn't actually costing the airline its face value. Example, you have a $300 viucher. If you buy a $1000 ticket that only costs DL $500 in actual costs, then DL didn't actually really spend/lose anything. However if they issue a gift card, they're actually spending $300.