> You seem to be hinting that [..] younger voters have worse decision making abilities

I'm not hinting at it - I'm saying so outright. Have your decision-making abilities not progressed since you were 16?

> How do you get out of the trap of thinking that people who vote in their self-interest or disagree with you are incapable of making good voting decisions?

The majority of people above the age of 21 will vote in ways I disagree with, so I don't see how it is relevant to raising or lowering the voting age.

> Teens who have jobs, pay income tax, teens who buy things pay sales tax

So because a kid can get a part-time job at 13, that should be the new voting age? Unless you put the voting age at 0, for some part of our lives, we all must live in a society whose laws we can't vote on. After that it's no longer a philosophical question of where rights come from, but a pragmatic balancing act between representation and an informed voting body.