Ageism is RAMPANT here in Iceland. It's insane. Some areas have taken to forbidding people under the age of 23 to camp at their campsites. 

We are not talking MINORS here, I can understand how the legal age can be used as a blockade, but people up to 23 years of age. What does this tell us?

23 year olds can:

 vote, be a cabinet minister, can have a gazillion children, own real estate, hold a steady job, have graduated from university, can fly airplanes 

BUT I'LL BE DAMNED IF I'LL HAVE THEM ON MY CAMPSITE!!

If drunken rowdyness is such a problem at your festivals - don't have them. 

If you cannot handle it - stay away from it.

You know it's gonna be a drunken fiesta, don't blaim it on your guests, blaim it on the people who HOLD the drunken fiesta every single year.

I betcha people would say something if people over the age of 40 were not allowed at certain campsites, or people with unequal numbers in their age or whatever. 

A drunken buffoon is a drunken buffoon at any age, and it is unbelievably unfair to blaim a certain group of people for everything that goes wrong - annually - at your own festival.