The reason they don't go after the top is because the top use expert tax lawyers to file. Anything they do that is shady is ambiguous in the law and thus had a theoretical basis. The IRS isn't taking on those people because if they lose in court, they lose the people who were paying extra by not exploiting the loophole in good faith.

Also, they say they are focusing on entities making over $400k/yr. I'm sure there are exceptions and trust issues on that statement. We'll see.