Research has shown that the human brain does not complete developing until our 20s and 30s. The frontal lobe, the part of the brain that manages impulse control, judgment, insight, and emotional control, is still working to make the connections that help us understand consequences of our actions for others and ourselves.
Teenagers are not fully capable of protecting themselves and in some ways need protection from themselves.
Teenagers are still children, incapable of consenting to a sexual relationship with an adult, which is why statutory rape laws exist.
Even when a teen is being abused, their age does not make it easier for them to tell someone and get help. In some cases, recognizing that they are being abused may make it even more difficult for them to disclose information.