I think someone has a litle too much time on their hands
It's just a lot easier for the buck. I mean if you think about it, it's not as easy to run through a crabapple thicket as it is an open field. Plus when she run's her body's rubbin against brush, briars, etc leavin scent making it easier for the buck to follow. Not that breeding in cover is exclusive. A few years back a buddy and myself were spotting and saw a brute mount a doe in the middle of a field. He hit it so hard he actually knocked her down