yeah not a big fan of that idea. I remember my political ideas when I was 16. I used to believe that social darwinism would be the best policy, to just rod the world of the weak, and the strong would prevail making the world better. I was convinced of this by my other 16 and 17 year old friends, who likely heard about it in one of their classes in highschool. in fact a lot of us believed this, as 16 year olds are really easily convinced of ideas that sounds good when spoken. It didn't take me long once I got out of highschool and started getting my first adult experience to realize how stupid that idea is.
The problem is high schoolers mainly experience the struggle of navigating social groups and are just trying to figuring out how to fit in with those around them. They are surrounded by peer pressure by those who also don't fully understand the complexity of social relationships. They are bound to have strong opinions based on little real world experience.
Not only that, it is easy to manipulate large groups of young highschoolers to believe what you want them to. Does anyone remember "The Wave" experiment where a highschool teacher was able to convert almost the entire student body into fascist beliefs before dropping it on them what he had done? I worry that if highschoolers are able to vote, that our already corrupt politicians will absolutely abuse that susceptibility to their own agendas.