Well if she just got out of high school, then she probably doesn't have any money, and it's probably her mom who's footing the bill for her apartment. Just because your kid turns 18 doesn't mean you're no longer obligated to care for them. I'm not saying the daughter shouldn't have to pay if she has money. If you do stupid shit, then you have to deal with the consequences; that's called being an adult. But it seems likely that the girl wouldn't have enough money on her own, and if this is the case, then I don't see how the mom going "You're 18, you deal with your shit now," is any better than what she's doing now.