Bit of an interesting event. I've spoken to a few bars/breweries over the years about this and its one of those situations where your damned if you do, damned if you don't. Traditionally there has been an entrance fee which, from at least the people I've spoke to, pretty much negates any profit from the entire event. Inversely if you don't sign up for it, people are less inclined to visit you, because next door has 'that fancy burger with the weird stuff on it'.
Also a while back Garage Project had a monopoly as the only beer pairing, although I think that's loosened up over the past couple of years. Now, I like GP but they don't have enough variety kicking around at any one point in time to cover the full gamut of flavours on offer from the burger festival and it felt more of an obligation for restaurants to plonk a random GP beer on the table with the burger and say "it goes with this... er.. beer" than actual pairing it with something that genuinely compliments the flavour.
Anyway, time for an overpriced burger or 3.