Question for electronics nerds

I know a bit about electronics and electrical theory. As an amateur radio operator, a big part of the licensing exam had to do with electrical theory, and I've done a quite a few projects in the past building things like radio transmitters and other basic projects, most of which use a 555 timer :). However, there's this aspect of electronics that's always baffled me that maybe someone can answer for me.

Why is it that it seems like with every device that has a digital volume control seems to have this point where one click is too quiet, then the next click is too loud. It seems that every device with a digital volume control I've used has this issue; my car stereo, my iPhone, my iPod, and so on. Just like horsepower and torque always intersect at 4242 RPM, there seems to be this magical point in electronics where need to be halfway between whisper quiet and ear splitting, and it's just not there. Is it a quirk of MOSFETs, a conspiracy, or something else?