I agree with your sentiment; people should be allowed to vote only when they have the wisdom to understand the issues.
The human brain continues to develop until about age 25. So, physiologically speaking, the majority of college students are NOT adults.
Kids who come out oif High School and go to work have a much better understanding of America and what makes it work, than kids who go to college and get their economic advice from liberal communist college professors, while heir parents or a govt. loan is paying their bills.