Two words - almost totally. Thru the use of trusts, holding companies, foundations, etc., it is possible to completely shelter from taxation a formidable amount of assets and income. In many cases, the complexities of this maneuvering are only worthwhile if there are considerable sums at stake - and then they become vital.
For instance, trusts can own real estate. Trusts can MANAGE real estate, and so can foundations. A foundation could, for instance, own (on paper) a huge mansion, and have in its articles that the owners of the foundations and their heirs may have full use of the mansion as a residence. As long as all of the i's are dotted and t's crossed, the foundation can provide for the "de facto" passage of the estate to as many heirs as desired. Of course, foundations must, by definition, make charitable contributions of about 5% of the assets of the foundation annually, so charitable giving is so channeled. To make sure the foundation never goes bust, the foundation (charitable, usually) must have income. That income is not taxable, so a wealthy individual can set up his compensation so that what he gets paid goes to the foundation.
I'm not a tax royer and have never played one on TV, but that's a simplistic explanation of how the system has been set up. There are plenty of other maneuvers, too - and the fat cats have cunningly made these avoidance plans available to all the top people in the media - all to keep them as willing accomplices. Which 'splains why the media are in FAVOR of tax increases - the hikes won't apply to THEM. When you read that a news anchor gets $7M a year, you probably think of a straight salary. Nope. No way. That 7M is sheltered 80 ways from Sunday against taxation - by the same cadre of royers who do Buffett's and everyone else's legal and tax work. You think Catie Colonic is paying taxes on her $15M income? Hah hah. I have some Arizona oceanfront property for you to look at.
Michael