Also, if you really want to talk about fairness and balance regarding gameplay, how about this:
- Current situation: tank is the superior killing machine. There´s not a single rival that can face it one on one, except another tank.
- Situation after changes: pedestrian/driver < tank < chopper. BUT a chopper will be beaten by a pedestrian (mini gun). Rock, scissors, paper. Everyone has to be afraid of someone else, nothing dominates, there´s no a perfect all-rounder killing machine.
I disagree with your initial premise: the tank is not a superior killing machine. It's horribly flawed to the point of uselessness.
Why? Because everything else in the game can avoid and outrun it, even pedestrians have passive mode. And pedestrians are more than equipped to destroy a tank, more so than anything else in the game.
There's literally only two ways for anything to get killed by a tank:
1) The tank driver used Off The Radar, worth one kill.
2) The "victim" allowed themselves to get killed by putting themselves in the tank's crosshairs.
Most tank kills are the latter example, where a player could avoid being killed by a tank but chooses not to.
A helicopter is not worse than the tank by any means. It's already a very clearly defined predator/prey relationship, where the helicopter is the predator and the tank is the prey. A tank cannot choose to fight a helicopter. It cannot attack a helicopter. It has no means to escape a helicopter and no means to chase a helicopter. It is only able to defend itself when the helicopter chooses to attack it.
If you're not talking about fairness, okay, then we're talking about two different things. But suggesting it would improve fairness somehow is flawed logic at best.
In their current state, attack Buzzards are really only effective with 2 people operating them.
This, as well. A passenger can aim the weaponry themselves.