When you are a child you have the mind of a child. It is by nature a self-centered view of the world with the base concern of having your needs filled. It is programmed into every human at birth and is not subject to alteration by way of status or location.
When you are an adult, you outgrow your child-mind and take on that of an adult - one that is able to look beyond self. As an adult you look at the bigger picture, the needs and wants of others and how it will affect more than just yourself.
The "many parents" you speak of here may know and understand this. They may see that their child or teen has not yet developed the mindset to look beyond self and to the greater picture of how it will affect everyone involved.
I would even venture to wager that these parents DO, in fact, listen to their children's opinions - and upon seeing the true nature of those opinions, help their child grow and learn by leading them to a more global state of awareness.
A parent who loves their child does not stand idly by and allow them to self-destruct. While a child may feel they are being unfairly treated at times; once they mature and look back upon the circumstances they will find that their parents did what they did out of love & to help that child grow to become the person they are today.