Is it common for professional drywallers to tape narrow corners, but not mud over the tape if it's going to be covered with moulding?
Personally I would not lose a lot of sleep over this.  The molding will probably cover it up.  If not have the contractor make the necessary adjustments.  Tape would still be needed for the seam that is above the door that we can't see in the pictures.  Do you feel that part of the seam was properly done?  There is also an indentation on the edge of wall board for the tape that might have been easier to fill with tape instead of just joint compound that shrinks and could crack.