In reading your lead expat Internal Revenue Service article I think it’s important to note that the FBAR form does go to the U.S. Treasury, but you must check the box and let the IRS know you filed one on the 1040 Form. Also, most FBAR filers MUST file the FATCA form and attach that to there 1040s.
The FATCA rules are much more comprehensive and this way the IRS has a double backup way of knowing what. Also, a second way to charge a penalty. With two penalty avenues and interest the amount can quickly reach $ 50,000 and become a felony. This can allow arrests at ports of entry into the U.S.A. at airports and border crossings.