I believe that it is a good idea that the minimum age for legal drinking has been raised, since it has many favorable reasons.
Also I’d like to make clear that consuming alcoholic drinks does not only have a lot of side effects on your body and brain, but it also puts one in danger.
Unlike drinking, voting and joining the armed services does not have as much direct impact on the individual; they are both like team effort, in this case, any mistakes or faults committed by one member can be corrected and eliminated by other team members. For example: The probability of bad outcome is less because the individual is not the only decision maker/actor.
Whereas in drinking, a person is solely responsible for his or her actions. That obviously requires a lot of responsibility and experience.
A person becomes more experienced and matured, as he/she grows older, hence somebody at the age 21 is more matured than at age 18.
In fact, I think alcohol should be banned just like drugs, because in most cases that makes a person (no matter what age) act irresponsible and violent and do things he/she wouldn’t normally have done if he/she weren’t under influence.
Yes, it makes sense that at 18 you can vote, get a job, serve your country, and drive.
Why can’t you drink? It will increase drunk drivers, which will lead to more death of innocent people, not to mention the addiction it causes which can ruin your whole life and in worst cases lead to death if not consumed moderately.