I don't think there is enough material to really constitute these as dresses, especially since they don't have backs either.
They are just very very very short.
They also look as if they are in the middle of a girls on cars montage in a bad 80's hair band music video. In fact as I write this post, I'm listening to Quiet Riot for inspiration. True story. And I want to bang my head against the wall after seeing this picture.