The difference is that APSA Councilship is likely perceived by members as a low-impact and/or thankless job, which very few want to be nominated for. Anyone who has served in faculty committees etc knows.
As someone who studies Soviet elections, I find the APSA ballot has a certain familiar charm. By their overwhelming unanimity, APSA members express their complete confidence in the Nominating Committee and demonstrate the unbreakable unity of the discipline.