They could have left the box blank, but they could not have left it off. Generally the cyan, magenta, and yellow plates would have been identical for all covers, direct and newsstand. The black plate was changed for the two editions, which is why you still have the box there in later direct editions, just with some artwork instead of a crossed out barcode. The plates probably weren't a huge cost on a print run like this, but being able to run all of the three colors for every book at the same time likely saved a good amount of press time, and that likely would have been the important cost here.