There is a considerable gap between the visual effects studios and the publishing legal firms. Lumping them together as the single "film industry" does not make for valid comparisons.
The visual effects studios have been big fans of open source. Usually it is difficult to "export" that code back into the community.
The biggest problem is that most code is intricately tied to the rest of the studio's pipeline. This creates a large amount of work to extract modules that would be useful for open source sharing.
The other problem is one of maintenance. There often is not someone with dedicated time to maintain a project that has been open sourced. This results in 'code drops' that end up drifting far from the internally used code.
Congrats to Imageworks and Disney that have been able to put the effort together.