In many years in Argentina I have always been asked for my DNI at supermarkets. Not so in all restaurants. They are usually satisfied with just the credit card. I've often wondered if the government monitors the use of foreign credit cards linked with DNIs.
I’ve Been using my US credit cards for almost 20 years in Argentina without problems. I’m using them now more than ever the past few weeks and no problems at all. And now that the white rate is higher past few months, I’ve even gotten secondary cards for my close friends and they just give me the cash. And all the better as I’m getting points!