As a past college professor of cross-cultural communication, I have taught about many cultures around the world, including subcultures within the United States (Amish, Jews, Native Americans), each having a ritual or custom that moves a child into an adult. There is no vacillation by the youth about the purpose of the custom — no confusion — except in the large culture of the United States.
For example, in the United States at the age of 16, a youth can opt to take a brief test and, upon passing, receive a license to operate a dangerous machine, the coveted automobile. Then, under current law, all male U.S. citizens are required to register with Selective Service within 30 days of reaching age 18. In fact, at age 18, youth will be allowed to do anything other adults do without parental consent: obtain medical treatment, enlist in armed forces, rent an apartment, buy a car, take out a loan, and in almost all states buy cigarettes and get married. In other words, all things an adult does — except one. The last initiation-custom in the U.S. for complete acceptance to do all that other adults are allowed to do is reached at 21: the purchasing of alcohol.
The U.S. might be better served if we had a single delineation of acceptance from childhood into adulthood — at which point no questions arise about enjoying the benefits or suffering the consequences.