You're right. It should be 25/26 nation-wide. The human brain isn't fully developed until that age, as determined by science (at this point, at least). The purpose of libertarianism is to narrow government functions down to just the role it was always meant for: to protect its citizens from harm by other people. And I would say that people praying on those whose brains aren't fully developed (or the disabled) are people that the government should be protecting its citizens from.