Ssimple actually.
If you see a collision, you'll take the damage from it. If he doesn't see one, on his end he missed, so no dmage.
Because of internet lag, what you "see" is not always what he "see's".
Even with good connects the other guy can often be 3 to 800 yards closer than you think he is.
Lots of people have complained about this . But the fact is all the alternatives are worse, way worse.
As long as we have internet lag we will have this collsion model.
The only person who can cause or prevent a collision is YOU!