understand it goes against their morals but I don’t understand why anything she does outside of the house is their business if she is an adult.
Some parents might be overbearing, etc., but other parents merely want some consideration.
For example, they may want advance notice of things like not coming home at night, not being home for dinner if the student is usually fed along with the rest of the family, and so on.
Every day in the news are stories of young people being found dead. Young people think it will never happen to
them but so did those whose bodies were found. And parents are past the phase where they think bad things won’t happen to them or those whom they love.
At a minimum, parents with whom one is living should know their plans so if nothing else, the parents can report them missing appropriately.
Letting them know you (generic) won’t be joining them for dinner on Friday night allows them to make less food, plan a meal you wouldn’t like but they do, go out themselves, etc.
And if there are younger siblings in the house, the older ones are still expected to set a good example.
From what you have said, your friend wants the best of both worlds: to be able to do as she pleases while living on her parents’ money.
Not very nice.