"What I read from this list is that the famous economists who work in taxation do not agree with this group on 'fair taxation.'"
The "famous economists who work in taxation" do not agree on much of anything in terms of a single plan that they all support. Therefore, if we follow their lead, the current system will continue to grow like a cancer, the trade deficit will continue to swell and Americans will grow progressively more frustrated each successive April 15.
We have absolutely no idea what a radical shift in the tax system will cause. Suppose we do it and the government can't finance its operations (such as the military). So, excuse me if some of us don't sign a petition on something that we don't know about.
As I said, I know a bunch of these people PERSONALLY and while I respect them, they are agreeing in theory without a clue of how it will work.
Do a web search for "public economics" or "public economists" and then find those at University of Chicago, Stanford, MIT, Harvard. Then cross list it with the petition. NADA!
Several people have attacked me for voicing an opinion - one that I am far more qualified to answer than virtually anyone on this site. Try doing some research before launching an attack. It is the same reason that I do not attack people who have served in the military.