Its a logic system. It takes ground where it is, so on a slope thats not even, it turns even without steering.
The fact that they heavily defy gravity while doing is is a bit of a bitch, but realistically speaking when we push it down the hill, would be odd if you could push i t back up (not that realism and crpg really match)
They are just not build for moving over hills, they work fine on flatground.
Love how this kind of things only get attention when you guys attack, but when you see it happen as defender :-|