Good luck with getting an anwser to that.
Younger ages the ball is not going over the fence so get the batter behind if you can, especially with 2 outs.
What do you consider younger ages? Around here, it's not unheard of for 10u's to be hitting the ball out. By 12u, it's relatively common. It slows down a bit at 16u as the pitching is more "mature", but still happens a fair bit.
Just curious - how far are the fences where these 10Us are hitting them over? I've certainly seen my fair share of "no fence" 10U home runs at various "fields"...but in 15 odd years at the league DD started at, the 10Us play on a field with 180 ft fences and I've never seen a 10U hit it out.
Not saying it can't happen but if you have 10Us hitting bombs on a regulation field, they really need to play up.