The credibility of (certain) characters

Both uppercase and lowercase letters are part of the de facto character set in our culture. But why is it exclusively latin and subsequent european writing systems that have two forms of each character? That peculiarity is virtually unheard of in the rest of the world and yet, astoundingly, our use of bicameral script is rarely questioned. This deconstruction of the phenomenon will tackle not trivialities such as orthography and readability, but rather issues such as religion, power politics and credibility.