You word your follow up post rather oddly in what capacity do you know the family?
Is it likely this is the kind of person that will just stay living with parents forever and having everything done for them?
Yes if they can get away with it
Or is there a chance they can go on to a have a healthy relationship and "grow up"?
There's a possibility they'd make minor changes, a nod to appearing more independent but fundamentally? No they won't change at heart. Too engrained by this age usually
Why do parents think that doing these things for their adult children who live at home is a good idea?
Well it's a type of dysfuntional, enmeshed, co dependent parenting isn't it? There's a similar thread running about an even older chap has his own place but his mother still does most of his chores and life admin for him, has a key to his place and comes and goes as she pleases etc
It can veer in some cases into something known as covert/emotional incest at its worst.
Where the parent and adult child effectively treat and see each other as others would a spouse sans the sex side of things.
It's more common than people realise but is still quite taboo to talk about. It's a form of parental abuse that usually started quite early in the child's childhood