Yes, I understand what you mean. The fact is that lag happens, mid-air crashes can't be accurately simulated the way you wish. Lag is also the reason GVs don't collide as a vehicle might lag into another vehicle causing a collision which sends them sailing (literally). As for hitting trees and such, it would be nice to encounter adverse effects if the plane actually hits it. However, there may be yet another reason as to why it's not coded yet.