Originally Posted by King Clark
Anyone not wanting our cash was happy to take our credit card.
Because of the magic of the international credit card networks, using an out of country credit card gives the merchant a transaction in his own currency no matter where the card is used.
That's a lot different from trying to use US currency in another country. Trust me, you may have been able to spend US currency in other countries but, as someone else has already pointed out, you probably suffered significant exchange rate losses compared to what you would have gotten had you made the exchange at a bank or simply used a credit card.
And, maybe with the exception of Mexico, Russia and some other third-world countries where people on the street want greenbacks, you preserved the impression of Americans as people who don't respect other countries and cultures.