Seventy-one percent of Americans agree with the statement, (76 percent were men and 65 percent were women). Twenty-seven percent disagreed with the statement. This can be traced back to the late 1960s and early 70s when the Vietnam War was becoming increasingly unpopular. The question was asked, if an 18-year-old can fight and die for their country why can't they vote or buy a beer?
With no good answers, Congress passed the 26th Amendment allowing 18-year-olds to vote. During that same period the majority of states lowered their drinking age to 18. The big difference was that in those days there was something called the draft and kids had little to say in the matter, it gave them a moral high ground on the issue. With today's all volunteer military, they can just say no.