All these answers are opinions from my perspective and they might be wrong and hence, I stand to be corrected.
I could think of two reasons. One, Cost of Education. In western countries like US and UK, the cost of education is pretty high. The cost just can't be handled by the parents alone. So, it makes sense for them to give more responsibility to the children and hence, reduce the burdens on their shoulders and btw they are not kicked out. The Parents prefer their spawn to take care of themselves. In case that they are unable to do so, the parents would take care of them (I know of few guys who are still living with their parents, even though they have finished their degree and started working).
This also tie-in with the second reason, Culture. While most western societies have changed to be more modern, many Asian countries still follow their traditional culture. Traditionally the parents took care of their spawn till they come to age or till they can take care of themselves and the Asian countries still follow it. Since the parents take care of the children, I would assume that the parents would think that their child has no good judgment and hence, they would personally feel obliged to make their child's decision but still, this only happens if the child has done some stupid mistakes in their lives or if the parent is too arrogant to see the capabilities of their children. In an ideal situation, the parent would make their child's decision until they gain better judgment and then, they would have a say in the major decisions but they won't determine it.
I think it, happened during the socio-economic boom of the 2000s.
The west, It helps the children to cultivate responsibility, both financial and personal before they forced are left alone in the society.
Both have their own plus points. With the western ideology, the children are able to adapt to the society more easily and with the eastern ideology, the children grow up having more respect for their parents, because many feel like that they are indebted to their parent to taking care of them until they can live on their own. In the end, it all depends on the attitude and the nature of their children.
