The assumption Congress makes is that to become wealthy, you have to earn income, which you were taxed on. You may become wealthy by inheriting assets, in which case you did not pay income tax, but rather estate taxes were paid. If you have assets, you can get money by selling them for more than you acquired them for, but this causes capital gains tax. Taxes are based on the flow of money, which in some way results in wealth. If you notice, wealth is always indirectly taxed. The system may not appear fair on the surface, but the wealthy will tell you that they do feel the pain of taxes. To answer your question, there is a difference, but not much.

You can have a high income (be seen as rich) and blow it all during the year (not growing wealth)
or, you can have a boatload of assets, not work, have little income, a be very wealthy.
Which would you prefer?

You may be on to something. You should send your idea to congress or better yet you should run for congress.