As an auditor, you surely know the difference between legally avoiding and evading. For Example, if someone gets a favorable tax treatment because they use LIFO inventory instead of FIFO, that's perfectly legal (at least back when I was auditing). LIFO may be a BS standard by any rational view for most companies, but its use for financial purposes is not illegal or immoral.
The examples you give are, with a few arguable exceptions (trusts, foreign income), illegal.