They have lawyers and tax accountants. Mitt Romney paid NO taxes for 10 years. That is why he did not want to show his taxes.
What FATCA will do is surge upward the renouncements and relinquisments of US dual citizens living all over the world. Most people don't go live in a country because of low taxes. They live for love of a person or the country. Filing US taxes cost thousands of dollars PER year now, even if one owes Nothing to the USA.
People will be giving back their green cards and many will be forgoing emigrating to the USA now the FATCA is law.
There is a growing boycott of not visiting the USA and investing in the USA. You run the risk of becoming a US person for life and having the IRS acess to your bank accounts forever.

There are 195 countries in the world 2 are citizen based , USA and Eritrea.
The rest are resident based. Resident based countries do not have their citizens file taxes if their money and investments are nit earned outside where they live.
There are only about 12 countries so far that have signed on to FATCA. All 194 are due at the end of the year to sign FATCA . Ha!
Reciprocity is promised in this law but this will not be kept. House Rep Posey wrote July 1, 2013 to Treasury that there will be no reciprocity. Congress Republicans refuse to have American banks report on foreign customers' accounts to those customers' countries governments for tax purposes.
The US A has its own tax evading post office box offices for those to protect and tax evade in the states of Delaware, Nevada and Wyoming. Lobbyists in the USA are ensuring there is no reciprocity. This will definitely give the USA a bad reputation, not keepung its agreements.

FATCA is a bad law and makes the USA a bully. Canada has not signed on as yet. Over 4 million Canadians will be affected. They do not want the IRS having access to their bank accounts. Protests are increasing.This law is going to cost millions of dollars for each bank to implement. All Canadians will end up paying for it, as citizens in other world countries. Some countries like Switzerland are closing americsn persons accounts, firing them from swiss jobs and canceling mortgages iii.