It has nothing to do with the way it was manufactured; rather, it was
*installed* upside down.

There is only one conduit, or clamp opening at the bottom of these
molded outlets. Mounting it upside down would require the feed coming
in from the top, which means putting 90's on the conduit. My cable
comes from the bottom.
Of course for applications where the feed comes from the top, then its
not a problem.