In the Artprize public competition, the public decides what is art. That's the rules.
In the Artprize juried competition, they decide what is art... for them.
See how easy that is?
It would be interesting to know if the jury would think that "Nights In The Light" is art. Alas that vote is already in. We'll have to wait for next year's inevitable balloon, pigeon, kite, etc. launches to find out.
BTW .. I think it's going to win and the artists names are Mike Carpenter and Dan Johnson.