The instrument touch down zone is 1500ft from the threshold, which allows for safe threshold crossing heights for large jets - which will also fly visual conversions to the same reference.
The point-and-power technique for light aircraft requires a nominated touchdown point and also some flex to allow for loss of power - so a typical RAF primary trainer flies about a 4.4° approach rather than a 3° approach (yes they do, do the mathematical calculations if you don't believe me!).
The higher approach speed and flatter approach paths of most fast jet aircraft require the sky gods, masters of their craft, to land as close to the runway threshold as is acceptably safe.