Why is it that air to ground kills give twice the amount of mission score than other kills?

A simple screen shot explaining what I mean:

For as long as I remember, particularly in ground battles (in the case of the screenshot above, it’s ground sim but it’s also the case for ground RB) you earn twice the amount of score (around 400) for every ground kill that you get with a plane or heli. While if you get an air to air kill, or ground to ground, or ground to air kill, that score is somewhere around 200 or less.

I have the same amount of kills as the guy playing in the helicopter, and with two captures, I have half of his score. What is the explanation behind this? What’s with the difference in score?

If the explanation is that you get more score for killing a unit of another military branch, then it’s utter horseshit because getting kills with SPAA gives you even less score than a ground-to-ground kill.