Yeah, I've had this happen to me a few times, mostly i let them pass if they're polite and have a really good reason, but if they're just trying to push through the line i'll just tell them to wait in line like everyone else!
The most annoying time was when I was in Gardaland in Italy during my vacation with the family.
I was waiting in a 30min line for the SLC, (which IMO was a nice, smooth ride, for once) and there were like 15 teenagers in front of me, most of them smoking (which in itself was extremely annoying) and suddenly a group of about 20 of their friends pushed past me. When i attempted to tell them to move behind me so they could wait like everyone else, i figured out only 1 person actually spoke any english at all, he quite frankly told me to piss off!!
Being set back in line a full trainful, especially with the poor loading going on that day, was really aggravating and almost ruined my day... As far as what the operators did to stop the line jumpers, they socialized with them.