Adult at 18?

Josh, an 18-year boy from the United States of America, has recently decided to join the American military. He is allowed to do so because he is considered an adult in America, beginning at the age of 18. He will then leave for another part of America, expected to go through vigorous training, learn important skills to survive, and more. All while not being able to have an alcoholic beverage because he is not 21.
Lizzy, 20, is a woman from the United States of America. Lizzy has a 1-year-old child, is married, and lives with her husband. Lizzy works a full-time job with real responsibilities, then comes home to take care of her child. Lizzy is considered an adult and fills her days with important obligations she is expected to. Although Lizzy has a house, is married, and mothers a child, she cannot legally have a glass of wine with dinner or drinks under any circumstances in America.
This is a reoccurring issue in the United States. Both Josh and Lizzy are just examples of the vast amount of people who do the same things as them, as well as many other varying examples in the United States. Many people see this double standard as a problem. Citizens between the ages of 18 and 20 in the United States are expected to carry out their lives as fully functioning adults, as well as the government, recognizes and tries them as legal adults, however, not being given the same right to drink that adults 21 and above are given.
This has led to many studies and research being conducted, as well as many conclusions drawn from them. The most prominent fact is that the drinking age of 21 does not stop all people under the age of 21 from drinking. This drinking age only makes people obtain alcohol in an unsafe way, whether it be from an unreliable person or source or someone they should not be in contact with. Whatever the case, alcohol is often obtained in an unsafe way, putting people in danger. If the drinking age was 18, people would not have to put themselves at risk to receive alcohol. In correlation with the unsafe way of obtaining alcohol, people will drink in an unsafe environment. This does not apply to everyone, although a vast amount of people are in this age category. If the drinking age was 18, these people could explore alcohol and do it in a safe, controlled environment. Whether this is the bar or another place where mature drinking is required. In turn, this would cause people to drink more responsibly and have fewer people abuse alcohol because it is not a forsaken thing. Alcohol is treated as a huge, exciting thing one can have when 21. Although, in other countries where the drinking age is 18, this is not a thing. Other countries do not make drinking alcohol seem like a privilege only adults have. From having a glass of wine with dinner to having the legal drinking age of 18, alcohol is not privileged. Because of this, it is not abused as much and makes the topic of alcohol an approachable topic with families. Unlike in the United States, where the topic is often discussed in the terms of ‘don’t drink it’ instead of a healthy, productive conversation. In connection with this point, fewer people would begin to drink a lot and abuse alcohol because it would no longer be a symbol of adulthood. Studies have shown that many people in the 18-20-year-old category tend to drink with the motive of appearing older. If the age were lowered, they would not feel the need to abuse alcohol to seem like an adult because, at 18, they are legally one.
Now think. How is Josh able to fight for his country and go off to war, but not be able to have a beer? How is Lizzy able to raise a child and get married, but not have a drink with dinner? The age for alcohol consumption in the United States of America should be changed to 18. A person going to war or a mother should not have all of the burdens of being an adult and not be able to drink responsibly.