You are arguing from the extreme Thomas.
First, it is reasonable to argue (and some do argue) that there is a body of knowledge, including scientific knowledge, that every citizen should have to make them a productive member of society.
General Relativity is certainly not part of this knowledge. To even have a chance to understand anything about General Relativity, you first need to understand vector calculus, linear algebra... getting the knowledge required to even begin the study of relativity takes several years of rigorous study.
The question of whether the average citizen needs to understand General Relativity is completely different from whether the average citizen should "believe" in evolution.
To be honest, I am not sure if I care what the average American thinks about evolution. It certainly doesn't matter to me what the guy who fixes my car or clears the clog from my sink (two people who perform important roles in society) think on the matter. I probably care in the case of my doctor (but maybe not even there).
The evolution case matters most in terms of the trust the American electorate puts in science. I would like people to consider the input of the scientific community.
But this is a political argument. Of course, the evolution debate is largely a cultural debate-- and in a multicultural democracy this is something we just need to accept.