The approach plate has the correct routing, which is curved (presumably to maintain the required distance from the runway centreline at that altitude) however if just transitioning, it's not normal to download and view the plate, so I suspect the majority of pilots relying on SkyDemon navigation simply route DCT, and thus stray from the correct track.

I was guilty of this recently - I was cleared to transition and then half way through "cleared to cross the extended centreline" which confused me, until I saw the chart afterwards... Even though I had been cleared all the way to VASSER originally, I was off course, and needed to be cleared across the centreline. The controller didn't explain why at the time, but I've spoken to other club members who have been "told off" for not following the correct routing.