That’s disingenuous - part of your compensation at many companies involves the expectation that the work is rewarding or its outcome has some non-monetary compensation. This is especially true in entertainment and media industries where workers will even be asked to work at a discount for the prestige.

Otherwise why do finance have to pay engineers more (at least here in London) or why are the interesting jobs nearly always paying below market?

If the show or film was cancelled after the worker signed a contract to work, the expectation of the worker when they signed up was that said work will see the light of day. Part of the compensation would be having the work on your CV etc and the prestige of your name on the credits.

The studio has reneged on an expectation the worker had when they accepted the contract and did not compensate them fairly for this new risk.