I'd say it doesn't happen as often as it used to (in the 70's) but I'm sure it still happens.
As far as the head butts....Remind me to not stop by "unprotected!"
Another tip for instructors who teach children lol.... practise Thai leg blocks! that way when you get an annoying child who likes to kick you you can block the kick without harm to you and they go screaming off to mum who then, as she didn't see anything untoward that would hurt her little darling, tells them to run along and stop being a wimp lmao!
In this country (prob do in other places too) we have challenges to fights in car parks, usually pub ones. They are actually very 'civilised' affairs with the fights being fair, one on one and with more or less boxing rules. I have a dvd (shh) of such fights, it's mostly gypsies who fight but others do as well.
The organised fights among the football supposrters are something else and nothing at all to do with martial arts. They are nasty, bloody and often with knives ( another reason to ban knives her)