What is behind the US Census Questions on Banking?

Last week, while at my cousins house, she was visited by a lady from the US Census Bureau about some 16 month survey that her house is now part of. After the usual spying on people --- the lady said that the FDIC paid for the the next set of questions, then some nonsense about confidentiality. The questions asked if the interviewees had a saving or checking account. If they ever cashed a check at a store or kiosk (Walgreen or Walmart). Every purchased a Money Order. Ever sent money overseas by a Money Order. Ever pawned anything or took a payday load. Most my cousin answered NO. But what were they looking for? Are they seeking people who are using cash to do transaction without a bank record or are sending money oversees to be converted to gold? Will the people who answer yes, be arrested?