Sure, everyone is happy with normal tax planning.<p>But some of these tax avoidance schemes are only legal because tax authorities do not have the number of staff needed to investigate and prosecute all of them.  They use weird loopholes (which get closed, and which sometimes require repayment of unpaid tax) and bizarre corporate structures which only exist to avoid tax.<p>Tax avoidance has changed its meaning from normal tax planning to become that gray not-yet-regulated area near outright tax evasion.