18 yr olds...
Just remember that you are up there for safety, as well as service.
In my company we have hired one 18 yr old I know of (in the last four years), a couple 19 yr olds but the majority over 21 (and while we're talking about age, the highest around 45 yrs)..
Probably because someone over 18 could have had more life experience. For example, helped in a car accident or assisted someone choking in a restaurant (for extreme examples). And perhaps they would know, before applying with airlines as cabin crew, that in these already experienced sticky situations, they will either fall or crumble under pressure... or more positively may cope better than others.
Also, customer service experience is needed for a cabin crew position. How much customer service can someone have if they've just turned 18, finished high school working 1 or 2 four hour shifts a week?
I know every one is different, but wouldn't this situation be a common one as to why some people find it hard to fly at 18ish?
Just trying to see it from a recruiter's side.