In the US it's common for merchants to always take both, it's not so elsewhere. I did take a taxi once in the US that only took one and not the other - and not the one I had.
That ended up as a half hour drive around town looking for an outdoor ATM.
Another interesting "feature" of credit cards is that they tend to charge a percentage for foreign transactions, and so do the banks that back the cards.
In the US it's common for merchants to always take both, it's not so elsewhere. I did take a taxi once in the US that only took one and not the other - and not the one I had.
That ended up as a half hour drive around town looking for an outdoor ATM.