One of my esoteric interests is currency systems.  For example I wish the feds would stop handing the currency system over to Visa and MasterCard.  This posting by Stan Collender provides a treasure trove of insight into how hard it is to understand the forces at work when you try to shift how a currency system works.  And, it finally answers the question: “why do the dollar coins keep failing?”

• Retailers decline to pay the extra cost to shipping costs (i.e. they are heavier).
• The paper manufacture lobbies heavily and generates the usual fog of PR disinformation to undermine their adoption.
• The vending machine industry demanded to be paid to convert their machines.
• etc…  it’s a fun read, if your into this kind of thing.