Anyone can walk up to a tank and press CTRL to get inside. I believe this also works when human crews are disabled.
This puts them in a random spot, mostly the driver, and be unable to switch seats. In addition, they cannot exit the tank, they can only change roles, which blows up the tank.
This puts them in a random spot, mostly the driver, and be unable to switch seats. In addition, they cannot exit the tank, they can only change roles, which blows up the tank.