I know 12 year olds that are working part time to help raise siblings, and I know 30 year olds that have never left their hometown or read a book that wasn't required in school. Old people with lots of life experience don't understand data privacy and think climate science is a fad. Young people have a unique perspective on issues like education, social security, and economic investment in the future. Why is that life experience less valid at 12 than at 18? Why is life experience necessary at all?

Why does intelligence factor into your objection? We don't ask adults to pass a test, nor should we. While I object to you using "retarded" to call children stupid, your slur undercuts your own argument. Adults with intellectual disabilities are able to vote without any obstacles or tests. The average 12 year old is perfectly capable of understanding complex topics and making informed decisions. They may not make the decisions we would like them to make, and they may regret their decisions, but again how is that different from any adult?