Walter Williams sometime has his head up his ASS. Liberal Bill Gates and Warren Buffett and others would set the agenda....
I haven't read William's full proposal about this, but I suspect that he wasn't serious.
The problem that you point out is exactly what's wrong. But at the same time, it would make it abundantly clear who is actually paying the income taxes.
You wouldn't believe how many people still believe that the "rich" pay no taxes, even though the percentage of the total tax burden paid by the top 1% has almost doubled over the past 30 years.