I doubt people would go out of thier way to kill thier t buddies as it first of all wastes your time and it would be easier to kill innos, if its a troll who has no intent of playing then the person dying because of the tnt cart is partially their fault for not checking and for the nether trap I would simply say avoid going to the nether. It wont help a massive amount but then again I doubt it will be hard to implement so