Speed of Light and Invisible Hand

Einstein's Theories of Relativity are innovative, but with the exception of one feature, his Physicist Relativism is not.  It is preceded by Philosophical Relativisms such as Phenomenalism and Perspectivism, as well as by Newtown's use of the primary Relativist construct in Physics--the Frame of Reference.  Two characteristics of the latter are: the conditioning of any interaction with the rest of the world by its own unique motions, and the absolute dissociation of any two such Frames.  Einstein's innovation is the thesis that the Speed of Light transcends any Relativism.  Still, it is unclear how he reconciles the existence of a plurality of discrete Frames of Reference with concepts like a Continuum, or a Unified Field.  Regardless, his model resembles Smith's, which is constituted by a plurality of independent parts, the  motivation of each of which is transcended by the Invisible Hand.  Of course, the Speed of Light certainly exists, while the Invisible Hand remains fictitious.  Nevertheless, there seems to be no way to prove that C is not a constant within the structure of a Frame of Reference, rather than independent of Relativism, plus, the thesis that it is an absolute maximum seems similarly unprovable.