Aren’t device drivers compiled into the Linux kernel? I would think that support alone would be worth more than 1.2B dollars in collective time spent ironing t

Aren’t device drivers compiled into the Linux kernel? I would think that support alone would be worth more than 1.2B dollars in collective time spent ironing that out. I don’t really know but I am thinking their estimate is rather low for the cost to reproduce the Linux kernel. Edit: missed the link to a paper for the estimate.