Ugh, you mean it doesn't get better after 12u? We had crazy parents this weekend screaming BALK and RUN IT IN just trying to mess things up....I was really hoping it gets better!
For the most part it does get better. By the time they are playing V at the HS level everyone has pretty much settled down. You still get an occasional player or dad who is obnoxious but thats more the rarity. My college aged son umps and he pretty much refuses to ump anything under 12u. As he puts it "Dad, the kids are fine, in fact they are fun, its the parents, at this age, who think their son is the next Jeeter who I can't stand."
That does explain SOME of the quality of umps we get below 12u! 
We had one ump last year say "That's it, I'm done, this is my last game, I am not putting up with this EVER again, I am a MAN!!"...on the bright side he DID finish the game, on the down side he kept saying the words "I am a MAN I will not be spoken to this way" usually while the kids were in the batters box he could be heard grumbling.
Both sets of kids in the hand shaking line took great delight in saying to each other as they high fived "I am a MAN" while peeling with laughter at witnessing this poor MAN's meltdown, on top of typical abuse the MAN did receive two shots to the adams apple that day, our side wished him well and thanked him for finishing the game.