The financial services industry has bitterly fought Wal-Mart's attempts in recent years to get a banking license. Whether Bluebird will restart that battle remains to be seen. The service, though, may prompt banks to pay attention to customers who often get bad bank service or none at all.

"Anything that provides clear, transparent pricing for financial services is a good thing," Ellen Schlomer, the executive vice president of the Committee for Responsible Lending, said in an interview, adding that she hasn't had time to study Bluebird in depth.

Shares of Wal-Mart have gained about 26% this year. The company's motives for bolstering its financial services offerings are not altruistic. In theory, if Wal-Mart can make it easier for consumers to manage their money, they will spend more at the retailer. The timing of the announcement, at the start of the holiday shopping season, is no coincidence. Wal-Mart already has slashed fees for its layaway plans. Bluebird, though, will help the retailer all year round.

According to the FDIC, about 10 million U.S. households are unbanked and 24 million are underbanked. Wal-Mart also can afford to treat banking consumers better than traditional rivals because it is not dependent on fees for its bottom line. That is good news for consumers.