When Walmart and Target begin catering to you, you are an official market.  The “unbanked” have companies scrambling to attract them. 
As current conditions (low interest rates, conservative lending postures) have banks adding more and more fees, and losing more and more checking account customers, the numbers of unbanked have grown. 
This new market represents a growth area for payday lenders, pawn shops and check cashing services.  These companies are not new.  They have been servicing this market the banks miss for a long time.   What is new, is the insertion of Walmart and Target into the product mix.

Walmart offers check cashing services and a branded prepaid debit card, and Target also sells its own prepaid debit card and some of its stores offer 0% financing and layaway programs.  Beyond the money the stores make off these services, in the case Walmart, when the consumer cashes their check, they have a wad of cash and are standing in a store.  The consumer is likely to spend some of that check in the store.

In the case of debit cards, a loophole in the Dodd-Frank bill allows the merchant to charge for every “swipe” of the card, thus generating further income.  So much so, that some bank are offering pre-paid debit cards.

The pursuit of this market is hot and heavy and so are some of the fees.  This has, as you know, drawn the scrutiny of the Consumer Financial Protection Board (CFPB.)  There have been few rules laid down from the agency so far, but expect that to change in 2012.