I really don't want to start an arguement, but I just don't agree.
It's all about training & experience!!
Wether your talking about horses or kids/humans.
I would trust with my life my 10 year old cousin that grew up on a farm & had been taught the ropes & has common sense, can drive a tractor & car on the property & listens & learns from his elders, than one of my sisters 18yo friends.
The 18yo has no clue about pretty much anything, very vague & demanding, very spoilt, is never happy even with all the gadgets that get bought for her, brand new everything that gets broken & trashed. And recently drove me into a house in my sister's car, by just being plain ignorant & then laughed it off. - Just an example
The 10 year old is very smart & forward thinking, & can handle a lot of different situations that pop up.
The 18 yo..... well the lights are on but no ones home. And would crumble under sitiuations less than what my cousin could handle.