Let me put my point carefully. I think that people should pay their due taxes. But you can't blame people for exploiting whatever methods exist to reduce their personal tax burden. We all do it. Some are considered perfectly legal and ethical, some are legal but considered immoral, some are illegal by UK standards, some are illegal by international standards.
I think that a degree of data withholding ought to be practised by, especially, banks. The first link that you referred to was about tax evasion in USA, so it was criminal in the true sense of the word. But it was in no way, about master criminals, etc, laundering money.
The second link referred to Swiss banks levying a retention tax on savings accounts to account for taxation not paid in whichever country it was due. Exactly how that was paid to whichever country, it doesn't explain. So the Swiss banks side-stepped the issue of data release, within the EU.
But as you rightly point out, there is a limit when organisations such as banks ought to disclose the information that they hold. But those cases must be treated on a case-by-case basis, not a free for all. And, certain countries, where certain freedoms are suspect, ought not to have that automatic right to data.
So not only should the data release be treated on a case-by-case basis, but also the requesting organisation/country should be considered on a case-by-case basis.
I also fully support the sharing of data between EU countries to reduce the tax evasion. But tax avoidance will always be fair game. It's not illegal. I agree that it varies in its ethical or moral status.
