Actually in this case I had a positive USD credit/balance on amazon.com account due to giftcards I bought with bitcoin via gyft.com, same with amazon.co.uk with

Actually in this case I had a positive USD credit/balance on amazon.com account due to giftcards I bought with bitcoin via gyft.com, same with amazon.co.uk with giftcard bought via giftoff.com using Bitcoin again. 3-4 year old amazon account with long history of purchases going into 6 digits, no chargebacks (not possible obviously) and my Irish debit card also on file with them. The risk of fraud/charback to Amazon (either US or UK branch) was exactly zero with me.