They think they have been through the same problems and have the answers. Instead of arguing or yelling, or even saying they understand what you are going through, parents should wait for their teens to come to them about it and then offer to help their child out. A teen can figure out the small problems on his own. At the same time, parents should always convey that they are available to talk to their teen. Sometimes parents can make their kids feel too pressured.
Teens like to feel older and mature, and to figure things out on their own.
I think this helps a kid become more intelligent and more confident. A teen is never going to learn anything about him or herself if the parents just do everything or figure everything out for them. They may not ever think that they are pressuring their kid but in some cases they are. Parents believe they always have the right answers. Another problem is teens' appearance.