At work, I provide end-user support for imaging devices like printers and scanners for a specific manufacturer. Every once in a while, I'll have a customer demanding an explanation as to why his 15-year-old device doesn't have a driver for a recent OS. It gets under my skin that I don't know enough about the process to be able to answer properly. I asked around at work but got several different answers.
The most common answer I ended up with is that it's simply not practical to keep updating drivers for older devices as the user base for these products only gets smaller as time goes on. In short, 100% of the responsibility is on the hardware manufacturer to put in the work to obtain digitally-signed drivers.
A different but lone answer I received is that it's up to the OS vendor to grant permission to the company to create drivers and that, for OSs that are no longer supported by the vendor, permission/signing will not happen. This answer just seems wrong and a way to shift blame.
I'm just looking for a bit of clarification on how the whole thing works.