Rogue Leader said:

For all we know being a royal of Alderaan means you are trained in military tactics and doctrine along with politics. Makes sense.

Alderaan is peacefull planet of pacifist, I'm not sure they trained for military tactics. I think she's there to rally the people like Joan of arc. It is an emergency, and have not enough fighter to escort the ships properly.

In the world war there was pilots who was 20 yo, and commanded squadrons, it's not depending age, but experience and ability.

Cheers.