It is coding far beyond the reach of us mere mortals.
Just remember that what you see is not always *exactly* as it happens. Also, most times when a player "wins" a collision the other guy is screaming "THAT SOB RAMMED ME!", and most of the time a player loses a collision they exclaim "THAT SOB RAMMED ME!", and then there are those of us who just *shrug* and realize that allowing ourselves to get in to that situation to begin with is our own fault and that is takes TWO for a collision to happen and that it take TWO to "Head On" as well.
Whatever the coding may be, I think if there is a collision the damage model should be far more dire than what it is. I'd like to think when a Hurricane and a Zeke collide that neither plane would fly away. The few planes that may have the ability to survive a collision of any sort would be the SBD, P47, F4U, F6F, 190, and perhaps the P40. I'm sure there are other airframes known for their stoutness, but those are the airframes I know of for sure.