The notion of fault is irrelevant to the collision model. The collision model simply detects if there is a collision on the player's computer. Assigning fault to the player who didn't have a collision and punishing that player with collision damage is ludicrous. If there is a collision on both computers then both players are affected. It's the best system for dealing with internet lag but it's not a system designed to assuage player egos.
So if I'm flying a plane and I collide with another plane it's my fault?
But if another plane collides withe me, but I can't see that, it's their fault?
And if we bother see ourselves hitting each other it's both our fault?
Brilliant!!! Here's a cookie
p.s. thank gawd someone gets it.