You must look at it from the perspective of the Oligarchy: Wars, regime-changes, support to "moderate" forces, spying on the world just cost money. And you cann

You must look at it from the perspective of the Oligarchy: Wars, regime-changes, support to "moderate" forces, spying on the world just cost money. And you cannot afford all that by only taxing those at home. You need every dollar. So, you tax the expats (8.7 million of them!). They are abroad to work after all - they MUST have earnings. As an alibi for your new revenue source, you pass a new law (Fatca) while saying that you fight "terrorism, tax evasion and organised crime". Again! The game you have played so well (and so often) in the past still works. This time it's even easier: Expat "elitists" have no representation, and the Average Joe cannot think about Fatca when he comes back home - tired and overworked - after two jobs, worrying about his CC debt and plethora of other issues.