It's not your fault, as you've said the job market is tough out there, for a job with animals like that they probably had a lot of very keen applicants, and who knows why they chose the one they do, it could depend on so many things. I think after she's done the TAFE course your daughter might find things easier and the course might help to give her more self confidence too, and support from friends she makes during the course.
Sorry about Centrelink, they are like this with everyone, I think they are overloaded after the pandemic, and the amount of paperwork they need is ridiculous. Everyone I know who has had to deal with them finds it awful!!!