A romancização de Alan Dean Foster não oferece uma resposta clara (a resposta correta é "porque ela é a Shiny New Hero", com o subtexto de "somos preguiçosos como roteiristas"), mas oferece alguns mais clareza.
Ela adivinhou que ela seria capaz de fazer isso porque ela acidentalmente tirou Kylo Ren da mente e invadiu a dele antes
Ela levou algumas tentativas para ter sucesso. Não foi bem "instantâneo", embora não exatamente "anos".
If she could push [Kylo Ren] out of her mind and enter his, what else could she do? What might she be able to do with regard to someone else? Someone less skilled, untrained in the ways of the Force? The single guard posted just inside the front of her cell, for example?
He turned toward her, patently unconcerned and not a little bored. She studied him closely. As he was about to speak, she addressed him clearly and firmly—and not only with her voice.
“You will remove these restraints. And you will leave this cell, with the door open, and retire to your living quarters.”
The guard eyed her silently. He did not look in the least intimidated. Her confidence wavering as she shifted slightly in her bonds, she repeated what she had said with as much authority as she could muster.
You will remove these restraints. And you will leave this cell, with the door open, and retire to your living quarters. You will speak of this encounter to no one.”
Raising the heavy, black-and-white rifle he held, he came toward her. Heart pounding, she watched him approach. Was she going to be killed, freed, or maybe laughed at? Halting before her, he looked down into her eyes. When he spoke again, there was a notable alteration in his voice. It was significantly less confrontational and—distant.
“I will remove these restraints. And leave this cell, with the door open, and retire to my living quarters. I will speak of this encounter to no one.”
Por favor, note que anos de treinamento Jedi nem sempre são necessários para alguém acessar suas habilidades de Força:
Anakin acessou a precognição da Força como pré-adolescente enquanto Podracing
Luke entrou na Força para disparar suas armas para destruir a Estrela da Morte depois de um treinamento incrivelmente curto com Obi-Wan a bordo do Millenium Falcon, onde ele nunca treinou para mirar com a Força
EU / Legends canon está repleto de casos semelhantes (Corran Horn, Kyp Durron são 2 que instantaneamente vêm à mente)