Is is to be noted that your red herring has nothing to do with your absurd falsehood about "past performance".
As far as I can see, past performance and current performance, as well as the concerns raised by the folks in the threads all attesting to the absolute rejection of retail sales taxes with income taxes is plenty of proof of my position.
What I find lacking is any evidence whatsoever supporting the idea for any political support for federal sales tax along with income taxes coming from any quarter.
Lacking evidence on one side, in fact quite the contrary in nearly universally expressed opinion against both tax systems in place as the federal level demonstrates the future viability of expecting the same to continue for the foreseeable future. Especially as such has been the clear case from many decades now with ample oppertunities and proposals laid out that could have led to such.
Sorry your assertions are belied by even your own statements espousing the concern against such a tax system. A concern that is quite evident throughout the electorate.
The red herring here is your obvious one of trying to introduce a potential that has no demonstrable political viability at all, and a clear case against such in the attitudes of the electorate.
The situation as it exists without the combination of both taxes is a self evident one to any who care to even take the most casual of looks at the political climate in regards federal sales taxes with income taxes. With the electorate is solidly against it at all levels, it is political suicide for any politician to even begin to suggest such.
That's fact, not a red herring and it's exactly pertinent to the subject at hand.