Can you fly to Europe free with American Express and Delta Airlines?

I tried to send this question to American Express. Can anyone answer it for me?

I have a friend that has your American Express Platinum Card. He tells me he flies to Europe free using his AE card and his Delta Reward Points. I told him in my experience the flight might be free if you have enough points but you have to pay the taxes. I checked on a flight to Europe that was $1200.00. Using 40,000 of my points the flight was paid for but I had to pay $600.00 in cash as that was what the taxes were. He insists that he flies free and American Express pays for the whole thing. Could you tell me if he is correct?

Thank you,

Thomas Spero