Most states and countries punish criminals with fines, jail or death depending on the crime

Most states stop treating adults like adults when they commit crimes?

yes, you lose the rights to be treated as an adult, because you've demonstrated you can't be one, and consequently must be babysat

e.g., going to jail, your room and board, your exercise, your hygiene, and general behavior will be decided for you, in a way determined best for society