You could just give them all the right to vote and rely on the fact that young people tend not to vote. It’s about the closest thing to a law of sociology that there is.
I'm totally into this. Picking the age line is hard. 13 year olds can have very different maturity. But I don't think that matters. Many adults have similar maturity haha ;)
I'm not so sure on vote rate. I hope we might be surprised! Even if not 20% would make a difference in policy. If it was part of curriculum and we tried to give students more confidence in their own power it could have generational change. A lot of social change has happened this way.
I work in politics and it very much disturbs me how often you hear that 'my vote doesn't have any power so why bother' it's self enforcing BS.
