Let's try a concrete example:
Jane was hired as a contractor to deliver a business process application in C#. The contract to hire Jane was a work-for-hire contract without the explicit copyright transferring language... /end of example.
I would presume that Jane's final work product is an arrangement of previous work by Anders Hejlsberg (who lead the original C# development team) and other employees of Microsoft. Is this not a sound line of reasoning?