Very bad idea. For every person in the world who need not pay U.S. taxes -- which would be everyone in your system -- there is a simple way to avoid this "tax"

Very bad idea. For every person in the world who need not pay U.S. taxes -- which would be everyone in your system -- there is a simple way to avoid this "tax": not holding dollars. The value of the dollar would collapse instantly. This strategy has, of course been tried before. A good example is Zimbabwe, which devalued its currency by a factor of about 10^25 (!!) in a few years.