It's not a matter of changing work-for-hire. The difference is writers have a union, the WGA, which does collective bargaining with Hollywood to secure certain rights. Programmers do not.
Here's the relevant section of the complaint:
ALLEGATIONS COMMON TO ALL CLAIMS FOR RELIEF
10. Defendant WGA and defendant Paramount are parties to a collective
bargaining agreement known as the Television Film Minimum Basic Agreement
(MBA). The particular MBA at issue in this case was entered into in 1960, and
amended in 1966. The 1960 MBA as amended covers work that WGA Members,
including Ellison, duly performed during the period of the operation of that
particular MBA, including Ellison’s City teleplay, which aired in 1967.
11. Paramount’s predecessor-in-interest, DesiLu, hired Ellison to write a
screenplay for the Star Trek series. Ellison delivered the City script and the
episode based thereupon was aired during Star Trek’s first season. This episode
receives continuing accolades, has become one of the all-time money making
commercial favorites, was ranked as one of the “100 Greatest Television Episodes
of All Time” by T.V. Guide in 1997 as part of its 50 year survey; and “One of the
100 Most Memorable moments in T.V. History” in the 29 June 1996 nationwide
survey; and as recently as in its 20-26 April 2002 issue, T.V. Guide celebrated
Star Trek’s 35th anniversary featuring, of the hundreds of episodes since its
debut, the “35 Greatest Moments!” City was # 2.
12. Pled in haec verba, the 1960 MBA, as amended by the 1966
Amendment, provides in relevant part in Article XVIII (N) on page 27:
“ADDITIONAL COMPENSATION FOR CERTAIN USES OF SERIAL OR EPISODIC
SERIES MATERIAL[:] Additional compensation shall be paid to the writer of a
story or a story and teleplay for an established serial or episodic series television
film as provided in this Paragraph N…. If the Producer licenses or grants to any
third party the publication rights to such material … Producer will pay to the
writer an amount equal to fifteen percent (15%) of the Producer’s net receipts
derived therefrom. The net receipts to the Producer shall be computed by
deducting from the gross amounts paid to the Producer on account of such
license or sale of the publication rights, all costs, expenses and charges incident
to such licensing or sale, including royalties, commissions and other amounts
which the Producer is contractually obligated to pay by reason of such
publication or measured by receipts derived therefrom.” The 1966 Amendment
modifies that section by stating: “Article XVIII Compensation – The following
additions and amendments shall be made to Article XVIII (Compensation): …(viii)
In subparagraph (g) of Paragraph N the words and figure fifteen per cent (15%)
should be deleted and the words and figure twenty-five percent (25%) shall be
inserted in lieu thereof.”) Regarding merchandising rights the 1966 Amendment
provides on page 2: “(x) Insert a new subparagraph (m) of Paragraph N providing
for a five percent (5%) royalty on Producer’s net receipts as defined in
subparagraph (g) for merchandising rights under this Paragraph N.” Other
similar provisions entitle the WGA Member to receive 25% of the exercise of
dramatic rights, 50% of the radio rights, etc. Importantly, there is no language in
the 1960 MBA or its 1966 Amendment that abrogates or diminishes these
substantial rights accorded union writers under its terms, or narrows the
meaning of the term publication rights to include only word-for-word replications
of teleplays.
You can read the full complaint
here.
Edit: The question hinges on what "publication rights" means. I don't have a copy of the 1960 or 1966 agreements so I don't know how it was defined then. The WGA contends this means only a word-for-word reproduction; Ellison claims this is unfairly narrow. It would be trivial for a company to get around such a narrow interpretation.