It is the unbalanced position of evolutionists that they expect a more extensive argument covering a wider range of subjects regarding a designer than they are either prepared to answer or are capable of answering about random chance.
Evolution doesn't postulate the existence of any singular, intelligent being working behind the scenes to bring everything about. ID'ers on the other hand make positive claims about the existence of such a being, and so they are on the hook to explain how this designer came into existence.