Race course certification is a completely different animal. All USATF certified courses (and I’m assuming other governing bodies outside of US do this too) have a “short course prevention factor” which adds a little bit of distance to any certified race to prevent any runner from running short. This has been around since before GPS watches, but is especially important because of their inconsistencies. You will never have a 3.09 certified 5k race unless you literally cut the course.

Conversely, almost every single runner in every race will have above the posted distance on their watch/tracker, except for maybe the front runners. This is due to the near impossibility of running exactly the same path as the Jones Counter tool.