Why do we experience first Person view if we can imagine others?

If we perceive the world around as and derive representations from it, as the cognitive realist might argue, and if we can imagine looking at the world from an arbitrary perspective, then why does our awareness default to first-person view? This is a dilemma explored by Greg Egan in “Seeing Through”. Why is it that we don’t have access to a vivid third-person view, based on the same (imperfect) representations?