EVZ,
Made-up numbers here for illustration:
My front-end has my position at 200,6000,1845 and your position at 200,6050,1850 in the x,y,z world; close, but not close enough that my front-end detects a collision with your aircraft.
Your front-end has your position at 200,6010,1840 and my position at 200,6010,1835 in the x,y,z world; close enough that your front-end detects a collision with my aircraft.
You see the message that you have collided with me.
I see the message that you have collided with me.
Nowhere is there a message saying I have collided with you - because on my front-end there was no collision.
Why do you insist that I should also take damage?
It is a cold, hard fact that each player is playing against what their own front-end is showing them. If I hit you with bullets on my front-end, your front-end is updated with that data and you see/hear hits even if on your front-end you see an impossible angle for hits. Same goes for collisions. If I collide with you on my front-end but to your front-end there was no collision, I take damage because it happened on my computer. You are informed that I collided with you and you continue to fly away unharmed, because on your computer there was no collision.