Also driver and other hardware-specific code is more likely to have a smaller population of developers to tend and improve it, and a smaller population of users

Also driver and other hardware-specific code is more likely to have a smaller population of developers to tend and improve it, and a smaller population of users to care about getting it fixed, so minor issues will linger longer. (I had a look at the 'arm' ones, and many of those are in code specific to a particular board or other piece of hardware.)