In some families, if the child is already earning a salary that is enough to cover family expenses, he or she doesn't have to wait for the parent to request money before they can start assisting the family. Some will even ask the parent to stop paying rent and use the money for other things. It's just a matter of self-decision. If you are to talk about legality, the girl is off-aga and is entitled to pay her own bills where necessary.
A responsible child will not wait for the parents to ask before they support the family. Any child that values their parents will not wait for them to say a word or even complain about house rent issues, feeding issues, before they step in. Do you know the struggles parents go through in training a child? Like, when you start earning, it's a blessing for you to be able to take care of your parents while they are still alive.
A lot of people, once they start earning, they are desperate to retire their parents and pay off mortgages, and just let them live a soft life. Because when you honor your father and mother, there is a blessing coming from it. So the girl really has the guts to complain. If they didn't give her education and training, she wouldn't have gotten a job. Like, she wouldn't have had that life she has. And if she thinks it is easy, maybe she could try living alone for a year and see what it means to pay for your rent.
She had better make a better choice of supporting her parents and going the extra mile to make them happy before they leave this earth. Because, truth be told, when parents grown a child to a matured age, they are coming to the end of theirs. So, yes, it's not an issue at all.