[ryao]

In the case of Nvidia's modules, Nvidia's proprietary licensing disallows distribution of a prebuilt nvidia.ko (as that implies distributing a modified version). Coincidentally, their license terms for the OpenSolaris driver have no such restriction and the OpenSolaris descendants distribute the prebuilt module without potentially violating Nvidia's license terms.

Amazingly, their Linux licensing used to be worse. They used to claim you were only permitted to install the driver on one computer within an organization