Great ad, Bill!
By my calculations, roughly 20% of the adults at the 10u level at any given tournament have personality disorders that hamper their view of reality. In other words, they lose perspective of the purpose of the sporting event in front of their eyes. By 16u, that percentage has dropped to around 10%.
These coaches AND parents forget that, first and foremost, this is a CHILD'S game - not an arena gladiator's battle. The worst part is, these adults do not understand the negative influence they are having on the kids around them. Kids aren't stupid - they are usually embarrassed, afraid, and certainly don't want to be around these people. They KNOW it's wrong, and certainly not FUN! This game goes WAY beyond winning and losing for the kids; it is a social 'playground" for them, and it's just flat-out wrong for misguided adults to rob them of an enjoyable experience. This is a prime reason some kids drop out of softball - they don't like seeing it bring the "bad adult" out. They still like softball, but they sure don't want to be around those adults - so they subconsciously give up both.
So... what can be done? First, you can't control the actions of other people, coaches or spectators. BUT - you can control your association with them. Second, use a "nasty situation" as a learning experience for your daughter. Talk IMPARTIALLY (just facts - not judgement) about a nasty situation at a game she witnessed. How would she have handled it? You can get a ton of insight from the players about these things, and isn't that what matters most? By doing this, you teach your daughter proper and civilized methods of dealing with unreasonable people.
In the end, you cannot control these people's actions. But you can control your daughter's perception of what is REALLY taking place.