> Who pays taxes when it's well known that the IRS doesn't audit and follow up on tax cheats?

But they do. They always have. The question is, once they've done that, should then they proceed to audit an even larger number of mostly innocent people, because a small percentage of them did something wrong and finding that small percentage would cover the costs of the IRS, but not any of those other innocent people?

> Especially, if all it takes to further dissuade them is engineering complex wealth structures and keeping tax lawyers on retainer.

This is an entirely different problem. The ones with sophisticated lawyers aren't actually violating the tax code. The problem there is that the tax code is so complicated and poorly considered that fancy lawyers can find ways to avoid taxes without violating the law.