I strongly believe that having a concert or a performance restricted to18+ is more than unnecessary, it is an outrage.
More than often, the majority of an artist's fan-base is under 18, in the 10-20 age group, so what sense does it make to restrict a show to over 18? As a 15 year-old musician, I find it almost insulting to have an 18+ concert, it's essentially saying "You're too young to understand or enjoy our music, so you're not allowed in our concert." Being 18 or over does NOT mean that you have a greater grasp on an artist's music and it's not fair to those of us under 18 who aren't able to attend said concert or performance. And then there are those concerts that are 21+ which is understandable, considering the drinking age, etc.
In short, I propose a change from 18+ Shows to All Ages shows.
