The misleading headline quote is contradicted by the article.
Yoona can’t become an Australian citizen without giving up her South Korean citizenship — something she isn’t willing to do.
She literally has a choice. She could choose to give up her SK citizenship. She could also choose not to travel at all. Those might have a lot of downsides, even worse than the $1475 fee, so she might be making the best possible choice for her, but it's still a choice.