Who writes the drivers for this software that 'Just Works'?

Over and over again I see commercial OS vendors implicitly credited for writing drivers that were actually supplied by the hardware manufacturers themselves.

The vast majority of the general population find that their Windows and OS X machines 'Just Work' because they come preconfigured with all of the manufacturer's drivers already installed.

Linux can't 'Just Work' in the Desktop space because:

1. It doesn't have majority market share (like Microsoft), so not all hardware manufacturers will make it a priority for their hardware to have good Linux drivers.

2. It doesn't control the hardware platform (like Apple), so it is likely that a significant proportion of users will have machines that have unsupported / badly supported hardware.