Jax
Look at the back side of the Jepp Airport Chart (10-9), there is a listing of all the distances--Glide Slope touchdown point is about 1300'-1500' feet from the threshold, TCH on the GP is around 45'-55', so where did you learn that a coupled ILS touches short of the pavement?
The electronic and visual paths may not coincide because that are not collocated on the runway side.
GF