> Drivers are specific to an OS, calling them proprietary is redundant.

Not at all, proprietary means it's closed source it has nothing to do with which OS it's for e.g. Nvidia has proprietary drivers for more than just one OS.

This leads into the rest of your comment in that Apple doesn't need to flat out make Linux drivers as a service to the community (though that would be great) rather they could simply share the info needed about their existing software or about the hardware so the community could focus on coding a driver instead of reverse engineering proprietary hardware and software.