That is flawed logic. The law has long recognized that certain rights can be restricted over the age of adulthood and others to those under it based on their capacity to exercise the right responsibly. We all have seen 18 year-olds who can't drink responsibly, hence the reason nearly every state's drinking age is 21. The age at which someone should be allowed to undertake an activity that may be harmful to others should be based on the age at which most people that age can handle that activity responsibly.