......but all duties, imposts and excises shall be uniform throughout the United States.
Next time you go to your smoke free restaurant, I want that $4 per taco tax imposed on YOU, you'll be singing a different tune very quickly when your $3 meal costs $15.
States were clearly given the right to tax as well not simply the federal government. I would stop eating the taco and buy some ground beef and a shell and make my own. Failing that I could, if I was so inclined, make the shell from corn meal, and raise my own cow. Hence the term no unavoidable tax. The states are not restricted from levying taxes, however congress is restricted from mandating an unavoidable tax and any taxes they do levy must be uniform.