There are Festivals that use barcoded passes, not Folk Festivals as far as I know but once it becomes cheap enough and understood properly .............

Les Barker has already written "Bark Odes" - but I sense there will be more.

They are doing similar on clothes now, with RFID tags. It could be done with passes. You don't even need to stop people to read the ID unless the alarm goes.

I predict one or more of the above.

But just don't ask me to put a date on any.