Regardless the age, all people including teenage under the age of 18 should be punish when they commit a crime. Weather it is on purpose or not, justice must always be done.
Punishment is also part of the education. This means that through punishment, everyone who commit crime could learn that all of their action weather if its good or bad has a consequences. Especially for teenager under the age of 18, they will learn this early on to be responsible of their action and minimized the chance of committing crime in the future. In addition, punishment for people under 18 is also part of justice for all. This means that all people is equal in front of the law, they cannot use the reason of being under 18 to commit a crime, misusing it as a shield to escape from the law, this will minimize teenager who commit crime on purpose.
One of the most important thing is to prioritize public safety. Some people commit the crime on purpose and repeatedly, this will threaten public safety. Re-education itself might not be enough, without punishment, underage criminals will think that they could get away with crime. Light punishment such as social activities which includes cleaning the road could be the punishment for minor offenses, while for major offense, strict supervision or even youth detention centers for period of time depending on the consequence of their crime might be an option.
In conclusion, all crimes should be punish equally according to the law and the punishment will act as an education for criminal offender.