Demonetisation: What India needs to turn into a less-cash society

Ancient cities had walls and gates to act as a checkpoint for defence, taxation, health, safety, etc. These gates would typically be locked after sunset to prevent unauthorised people from entering, and more important, to guard against a surprise enemy attack. Modern cities are more open. While toll plazas and tax checkpoints do exist, cities are open and usually allow for free movement within the country.