Yes, festivals are expensive to organise, no I don't expect children who are taking up a place in a concert to get in free, BUT.. if the cost of taking a family to a festival is too high, those with children will not go thus losing both the price of the parents tickets and the chance to encourage the next generation who are the festivals future customers. Also when someone does not camp or go to a festival for a few years the idea of "camping" tends to appear progressivly less attractive, so they may not return even when the children are gone. Some festivals do cater for younger festival goers with a variety of suitable workshops and activities that are an alternative to the formal "adult" concerts. This usually means less bored (children in general have a much shorter attention span) potentially disruptive children in the concerts. Unfortunately most festivals do not allow people to camp and pay only for the camping without buying a full festival ticket. An alternative that would probably appeal to those with teenagers who are only there because they are too young to be left at home on their own, currently get charged full adult price but don't go to a single concert, preferring to "hang out" with other youngsters their own age.