I have never seen the setup so not sure if its in the same place or if has moved but the facility at Latitude has been available for years.
Part of the problem is The Licensing Act 2003 which came into force on 24th of November 2005 mentions the words ' at the point of sale ' and do not cover wrist bands at all so anyone who hands out over 18 wrist bands to people who are under 18 is not breaking any law.
From bar experience at Latitude most people { under 21 } tend to carry ID anyway but it would save them having to carry it and cut down waiting time if the over 18 wrist band system was made to work.
I have seen young teens who no would think they were over 14 never mind 18 walking about with them - they did not try to buy alcohol but that is not the point because as soon as one is spotted then clearly something has gone wrong.
If I get time I will visit the over 18 wrist band tent as I want to see it in action and see how strict they are as by now there should be very few mistakes.
Glasto 79,81,82,83,84,85,86,87,89,90,92,93,94,95,97,98,99
Glasto 2000,02,03,04,05,07,08,09,10,11
Reading 1989,90,91,92,93,94,95,96,97,98,99
Reading 2000,01,02,03,04,05,06,07,08,09,10,11
Latitude 2006,07,08,09,10,11