In my opinion, this is more directed at the child's own awareness, if the name of the parent certainly does not want to burden their child unless they are in need of funds when there is an emergency. Well, if the child is already working and has an income, then it is natural for him to give some of the results of his hard work to his parents, but if he does not give some to his parents, it is wrong, because giving some of the results of his hard work to his parents can be said as a sign of gratitude even though sometimes parents like to say it is not necessary, but I myself feel how happy I am when I can give some of the results of my hard work to my parents. Apart from that, I think it is impossible for parents to collect rent from their children who live with them, this is very odd and ridiculous if there is. Usually parents will ask for money from their children who already have an income for other things such as maybe asking for help to renovate the house, or school fees for other relatives, but to collect rent to live with them is ridiculous.
I think that is not good to take rent from that child because they are part of the family and they should distribute most of the expenses . There are many people who have have that kind of system but that is common on European countries. That is not common in Asia because most of the persons of family care each other and they always try to care each other when any unexpected situation happens.Every country's people have different society and many parents want their safety because sons and daughters always try to escape their parents from the home . Parents should be kind with children and if they are not kind then their child will do battles.
That's why I say it depends on the child's awareness, not the parents' request.
It is not very ethical for parents if they still expect what they have done for their children and want to return the favor because after all it is a condition where the obligation if they have children then before the child becomes an adult then the parents must be able to provide good service as a form of their responsibility.
If in the end one day when the child is an adult and already has an income when they want to give then it does not matter but if in the end they do not do this it does not matter because parents do not make this a debt burden for them (children).
The problem is that sometimes for now there are still quite a lot of people who always use this as an excuse where they always try to use children so that they can become a gold mine for them as if children are an investment for them so that they can not work and live, although indeed things like this are also a fairness for some people but for those parents who think more logically I think this condition will not happen.