Mock cables, in a gist, are stitch patterns that made to look like cables but employ other techniques to create them. There is a number of ways to create mock cables, from twisted stitches and slipped stitches that snake atop of your fabric to a whole variety of decreases paired with increases, or even decreases and yarn overs. What they all have in common, is that there is no that usual crossing of the stitches or rearranging of the stitches and working them out of order that we associate with regular cables.
Both Simonside and Bowburn use the latter type of a mock cable I described, where you use decreases and increases to make it up. They are in fact a pair of ribbed hats.
Simonside sets off the stocking stitch wing with a true cable, you can see the first twist right next to the ear here. After this twist, however, the insertion is shaped with increases and decreases and kind of flows across the ribs to the base of the crown. A super quick knit worked in an Aran weight yarn.
The interlacing rib of the Bowburn hat is another good example of what can be achieved with this technique. The crown shaping here grows naturally from the pattern below, taking this interwoven trellis rib to the tip. You can't really distinguish between the stitch pattern and the crown shaping without careful examination and I am rather taken with this one in particular because it looks more complex than it actually is.