Pros & Cons of Concert Age Restrictions
Deciding whether or not it is necessary to enforce age restrictions for events (specifically for electronic music) varies from person to person ultimately depending on how old they are themselves. Someone who isn't 18 years of age yet might be the first to jump on this question and complain about how unfair it is that venues and companies are "discriminating' their demographic based on age. Those who are over 18, will either be indifferent to the decision or annoyed that there are a bunch of underage kids running around; either way, it probably won't matter so much that they decide not to attend that event. Companies who are hosting the event however, can look at it from a safety, marketing, or financial perspective.
Under 18 Perspective
Having underage people at a concert can be good and bad. Like I said earlier, for the rest of those who are older, kids can be immature and disrupt the general atmosphere by being obnoxious and out of control. Since they aren't really exposed to events as often as older people are, kids can tend to go a little crazy given the opportunity to party with friends without being under parental supervision like they would at a house or school party. I personally have met people who are under 18, who use an older friend's ID to get into the venue. So, if a kid REALLY wants to attend a concert where there are age restrictions set, chances are they will find out how to get in one way or another.
Over 18 Perspective
Festivals and concerts usually require the attendee to be at least 18 years old because at this point they are all legally allowed to make their own decisions without parental consent. Anything they choose to do at the concert will be their own responsibility and nobody else's. It's smart from a company's perspective because they avoid the possibility of someone underage getting hurt in any way, in which case a parent or guardian would have to be contacted which may in turn result in legal troubles. As a fan, I personally would rather an event be open to 18 or 21 year old people because kids are more likely to do something irrational and stupid, putting the venue at risk of having to be shut down as a result of an adolescent's poor behavior. That being said, seeing the caption "all ages permitted" under the title of a show or festival I'm really looking forward to isn't going to be enough to completely change my decision of attending. So I think it's safe to say that having an age restriction for those in this age group really doesn't have any real effect on their desire to go. The worst part would be having to ignore any irritating underage activity which really isn't that much of a burden.
Company or Venue Perspective
Age policy decisions are made in the hands of those who are running or hosting the event. Most people may think that companies might as well play it safe and enforce the 18+ age limit to avoid many of the problems previously discussed, but as business people, there are lots of reasons as to why age can make a huge difference regarding the success of the show.
Marketing is huge in the entertainment industry. Without promoters and advertisements, how would the general public find out about their events? If the age demographic was limited to only those who are say 18-35 years old, it might be more difficult to bring in people who will want to go considering most people by this time are either full time students or have full time jobs. Either way, having a "real life" with adult responsibilities and obligations can often make it harder for people to spend that kind of money and take time off from their job or school. Kids in high school, are usually free every weekend and will want to do something different every now and then as opposed to going to the school football game or hanging out at a friends house every weekend. Reaching out to the high school age demographic can be beneficial because it greatly increases their publicity rate.
Financially, having an all ages event can be GOLD for companies for many of the same reasons associated with marketing. If kids in high school want to attend a show or festival, chances are they can easily convince their parents to help fund this activity since it's not something they get to do every weekend. Adults with jobs or those focusing on paying for college often don't have hundreds of dollars to be spending on tickets (not to mention travel/lodging for festivals). Inviting people of all ages will greatly increase their chances of hosting a sold out event which obviously boosts their total revenue creating a good reputation for their event in following years to come.
Safety would be the one factor that stops companies from allowing all ages to attend. It might be rewarding to have a festival with a sold out crowd, but will it be worth the legal obligations if someone underage were to get hurt in anyway? That's why age restrictions can be a very controversial topic within the entertainment industry because the pros sometime level out and equal the cons. If successful, an all ages event will probably give that company and event a great reputation and a high income. But if something involving a minor were to go wrong, bad publicity will be extremely detrimental for that event and may possibly prevent it from ever happening again. For some companies however, that's a risk they're willing to take.