The government of the United States is one of 2 in the world that taxes based on citizenship. Ex-pats who live, work, and pay taxes in foreign countries are currently still required to pay taxes to the US government. These taxes are IN ADDITION to the taxes we pay to the foreign governments of our adoptive countries.
The Foreign Account Tax Compliance Act (FATCA) has given the US government the incredibly pervasive new power to compel foreign governments to report on the assets of Americans anywhere in the world.
It is unfair and out-of-step with the rest of the world to tax your citizens like this. Put an end to taxation of Americans abroad so we don't have to continue renouncing our citizenship for the financial good of our families.