Pew Hispanic reports that in 2005, the 6.6 million illegal immigrant families in the United States had an average annual income of $29,000, and accounted for nearly $200 billion in purchasing power. But 30 million foreign workers—legal and illegal—are said to lack bank accounts. Citigroup Inc. and Bank of America have tried to tap into that market by making credit cards available without a social security number. (Other safeguards are in place, such as the requirement that an applicant have a Bank of America account in good standing for at least three months.) Nonprofit worker centers in Hempstead, Chicago, Los Angeles, and the New Labor Center in New Brunswick, New Jersey have begun to offer debit cards to immigrants.

What problems are solved by such credit/debit cards? Created?