It took a while for forward thinking technical managers to convince studio executives that open-sourcing some internal tools and data formats would benefit the studio by making it a standard within the industry. OpenEXR (image format, ILM), Alembic(data format, Imageworks), OpenSubdiv(subdivison surfaces, Pixar), Ptex(texture mapping, Disney) are examples that were quickly adopted across studios. It helps that artists and engineers tend to move across studios bringing with them ideas about what worked best at the previous studio.
In general, the software teams at the studios fall under the line item of "Overhead" in a producers financial spreadsheet. There is pressure to reduce this overhead by adopting standardized tools and not reinventing things in-house.