At 30m range the arc would only be a few cm...10cm at most... unless the bow was very weak and had a low draw weight. It is not until you get to over 50m that the arc is visible to be honest though I do agree that it is significant at 80-100m.
Remember that we may be accustomed to the Hollywood representation of a large group of longbow shooting at a distance of a few hundred metres. There, you just aimed high knowing that, as a formation, your arrows would fall in a broad oval somewhere in the mass of men coming at you.
When target shooting to hit something man-sized at a range of a few tens of meters, there will be no visible arc.