How does NERV managed to avoid angels attacks everywhere else but Japan? Did other countries found japanese EVAs a thread to themselves or they just felt pitty for this giant monster infested archipielago?

The Angels focused on Japan because Tokyo-3 is where the embryonic state of Adam was smuggled to in order to be experimented on by the NERV organization, after its discovery in Antarctica during the Second Impact. The Angels, who wanted to destroy humanity and repopulate the Earth with the offspring of Adam, saw the recovery of Adam as a main objective.