I have to say, I'm surprised as well, considering that the numbers are for a couple. It may be doable for frugal people, but articles like these usually do not assume that everyone is frugal. I am particularly astonished to see that they estimate a couple's monthly expenditure at USD 1,185 in the south of France, but I haven't been there, so hey, maybe it really is that cheap.
I see here that the numbers include:
Monthly budgets consider the following costs: rent for a one-bedroom apartment, groceries, utilities, cable, Internet, phone services, and entertainment (eating out twice a week and two trips to the movies a month).
So, no medical, no transport, no insurance, no trips back to visit family/friends, no non-essential purchases of gifts or other items, or even for things like furniture, bedding or kitchenware (but perhaps the apartment is fully furnished, though it doesn't specify that), etc.