On top of Herod's points, mil jets generally fly visually judged approaches, for which the piano keys/numbers form the most obvious aiming point, whereas commercial aircraft will more often fly a radar or internal aids approach, which will bring them down between/next to the PAPIs/VASIs rather than on the threshold.
And commercial flights rarely go around, whereas a mil jet doing a touch-and-go will want to get on the ground soonest to leave the maximum amount of runway for the subsequent take-off.
And mil jets are more manoeuvrable than airliners, so there's a better chance of correcting an approach to the threshold if it becomes apparent that the aircraft is going to undershoot (no guarantee though, as the fence along the A15 at Waddington will confirm...).