TAIL WIDTH - shortboard vs. mid-lengths

I’ve been looking at intermediate level shortboards, like the Firewire Dominator 2 and noticed that the tail widths are wider than what I expected. My 6’9 egg, for example, has a 15.5" tail @12". Judging by the image in the link above with size 6’0 x 20.5" the tail @12" is 15.75". Is it correct to think that this works because the board length is only 6.0", and combined with the curved outline, it’d be easier to turn in? I know foot size comes into play here too. Im wondering if its reasomable to think that tail width can be scaled up as boards go shorter, provided the rocker is also adjusted.