In response to a new federal law limiting the hidden fees that banks can charge for using debit cards, Bank of America has announced that next year it will charge $5 a month to consumers who use its debit card to make purchases. SunTrust is expected to follow suit, as are other banks.

By some, this will no doubt be seen as another example of well-intended federal regulation with bad consequences. It’s quite the opposite. In fact, conservatives ought to love the change because it enlists market forces, not the government, in protecting small business and consumers.