According to Business Day, South Africa's plastic revolution is putting credit card firms in the pink. Cheeky title, but the subject matter is serious business - signaling that the formal economy is growing rapidly in southern Africa. Visa and Mastercard, the industry leaders, report annual growth of its credit and debit card user base anywhere from 9 to 42 percent (depending on the product).

Some growth can be attributed to South Africa's credit-access legislation, which prompted leading banks to introduce formal savings and credit programs for low-income communities. Visa's sub-saharan general manager "expects growth to be in excess of 100% in the region outside South Africa and 150%-200% in some countries."

200 percent growth in customer base isn't simply abiding by legislation - its a sign that credit companies are responding to demand. As access to formal finance improves, so will low-income communities' ability to reap the benefits of their local and regional economies.