injuries do happen by getting hit by a ball (hard, rubberized), stick checked and body checked.

DS has been a goalie since 2nd grade. Sometimes I wonder if Social Services is going to come knocking due to the amount of bruising on that child's body. As a keeper, he wears as little protective gear as he can get away with (it restricts movement according to him) and gets bombarded with a rock hard ball whipped out of a stick at enormous speeds. And this is fun???
I really don't know what happened like I said, I will however say that my niece is from an area that is known to be "rough" and they were playing in a town that is known to be on the snobby side. A lot of "snowflakes" in that town I'm sure. When I told my friend where they were playing she said, "Oh, someone's princes must have been bruised."
I find it hard to believe she would actually be clubbing players with her stick (she's my niece of course, so I don't want to think that)- her coach was not happy with the ejection and said it was completely over the top. I'm hoping my sister in law has video.
We have many leagues/teams around town that are from wealthy parts of town, from prep schools, etc. I can guarantee you that does not make their kids "snowflakes." In fact, it seems to be exactly the opposite. Snowflakedness would not be tolerated by these competitive parents. I know plenty of parents that pay their kids every time they are put in the penalty box. Our league director (a pro lacrosse player) told parents during our preseason meeting to please shut up on the sidelines about hitting (we would be in the medium snobby category), that it really is a game of skill and finesse.
In our area, both girls and boys, it takes a lot to get a kid ejected no matter what part of town they are playing in. The refs are really into teaching the kids the game before they hit high school, so only if the aggressiveness is purposely blatant and after several warnings will a kid get ejected.
That said, there is little leniency for coaches or players that are deliberately trying to play dirty and hurting other kids. They are all kids after all.
Unfortunately, we have a few teams that would rather go out and play like thugs rather than actually even attempt to play the game of lacrosse. There really is skill involved in the game, not just slashing and hitting. And geography has nothing to do with it, you have good and bad coaches in all areas. It all depends on their philosophies and what they are teaching their players.
So, if your niece was playing around here, I would have to surmise that what she did was over the top and was pretty blatant, although your refs style may be quite different.
Or, since you said her coach likes to play rough, perhaps the refs were fed up with his coaching style and your niece was just the last straw and a point was being made to the coach. Her infraction could have been minor, but could have pushed the refs over the edge. She may not have even known what she did was not acceptable, especially if the coach likes to push the limits on penalties. I could definitely see a fed up ref saying something like "It is a game of finesse" in frustration with a coach encouraging kids to play dirty or rough.
The good thing is that it is just a game and I bet your niece will never commit whatever penalty that got her ejected again. By being taught that whatever she did was not acceptable, she will be a better lacrosse player next game. Spin it into the positive - she made a mistake, she payed her dues, and for it, she now knows the game that much better.