Heck, they didn’t lower the voting age to 18 from 21 until the 26th Amendment in 1971. Before then a guy couldn’t vote but could be drafted.
And it was a mistake to do so. The maturity level needed to fight, and the maturity level needed to make responsible decisions about how a nation is governed are not necessarily the same.
This amendment was passed to give the draft dodgers political clout. At the very least it should have excluded everyone who didn't serve.
Want to vote at age 18? Join the Army. Just my opinion.
As a practical matter, 18 year olds voting has been a disaster. They are too gullible and too easily manipulated.
In South Carolina the legal age to buy and consume beer used to be 18 but the voting age was 21, now the reverse is true.
What is more dangerous, a can of beer or a vote?
When I was eighteen I could have driven down the road in this state drinking a beer and tipped it to a highway patrolman and it was fine as long as I was not drunk. Now the same action would get anyone of any age locked up. Things have changed a lot in fifty five years.