Originally Posted by
xliioper
Yes, I don't believe they actually enforce terms that say you must use card to pay for taxes/fees.
I usually put any DL purchases on the vanilla AmEx Platinum and I've never not received the 15% discount and never had the additional 15% clawed back for not purchasing a mileage ticket with a DL branded AmEx. Honestly never even realized it was technically one of the T&C.