Then you haven't been paying attention. Taxing Paul while not taxing Peter is market distortion.
Taxing apple sales while not taxing orange sales is market distortion.
If you are going to tax income, it's a moral failure to describe some folks income as not-income. Gingrich tried to do it with interest paid to banks, as if renting money were any different than renting land. Now the effort is to say that buying low and selling high is somehow protected as long as there is 6 months or so between the buy and the sell.