When it comes to preventing tax avoidance or evasion, it seems that many countries apply the principle that while making sure collection of their own taxes is high priority, enabling other countries to collect their own doesn't matter so much. The degree of secrecy taken together with the scale of activity in each country make for some surprises in the Financial Secrecy Index ranking of world countries by the Tax Justice Network.
Achetype tax havens like the Cayman Islands are high (#4) on the list for sure but it is refined, reserved Switzerland in top spot. Nipping at the Cayman's heels, ahead of Bermuda, Panama and Jersey, is the good ole USA in #6 spot! Why? Because while it is fanatical about collecting its own taxes, it doesn't bother nearly as much in helping other countries collect theirs. #17 Canada sins that way too, if one reads the linked country report, backed up by very detailed database info.
Let he who is without sin etc.