Banking in the Developing World?

"...Burro was functioning as a rudimentary bank for agents with no other savings account.  The company did not pay interest but did not charge any fees - unlike the informal local savings banks known as susus, which charged customers for the service of saving their money.  In the developing world, this is called negative interest."

From  Bright Lights, No City by Max Alexander, a great tale about selling rechargeable batteries in Ghana.  What do we call negative interest in the developed world?