Status Quo.
It is an absurdity to consider votes at 16 when you consider 16 year old children cannot:
(1) Drive.
(2) Get married (without parental consent).
(3) Leave school.
(4) Bar necessities, enter into contracts.
(5) Go into a pub and buy a pint of beer.
(6) Buy a packet of fags.
(7) Buy fireworks.
(8) and so on....
If society considers 16 years old children too immature to buy a pint of beer in a pub, on what planet are they mature enough to vote?
Of course we know why this argument is often trotted out by those on the left, because they know youngsters tend to be more left leaning - I certainly was. My daughter was 15 at the last election and they had a mock election at her school and she voted Labour because, she told me, they were going to scrap tuition fees. She had no answer when I asked her how this largesse was going to be paid for - I didn't expect her, and I wouldn't expect any 15 year old, to have an answer, but the point is if she was just 1 year older, she would have voted Labour based on an unpriced promise.
If 16 year old children are allowed to vote, then why not 14? or 12? And if not, why not?
18 in the UK is when children are considered to have become adults, and therefore 18 is about right.