Must be your upper lip. They have plenty of Treaties, just not these. I'm surprised at the hole in your knowledge, but not with the cat spiting. No one has backed you into any corner.
Maybe educate yourself, before you make predictions in Global Finance about what you seem to know not.
Are you actually suprised that the USA is not all powerful, all over. The Tangos are howling with laughter. They have their own private banking, stateless and secret.
Off shore banking has not been penetrated. All Europe, ie, Swiss, Liechtenstein are compromised. But, Charlie, not all the world.
Not India or Belize, Singapore and a few others. And of course, they still conduct International Banking with the Tax Signatory Countries. But, it is only numbered accounts. They are just not open to scrutiny, by the IRS, FBI, DEA, etc, and they did not take the drug enforcement money.
Simple as that.