They had no way of knowing what they were bringing forth.
Vendors were told to expect 200 people, and of 11 trucks, 3 had sold out within the first 90 minutes. The Meatloaf Bakery was out of goods within about half an hour. In the photo picture above, you can see people already waiting in line around 12:50PM in front of a sign that promised the truck would re-open at 1:30!
Curried Away, selling curried food, hurried away around 1PM, completely sold out of goods. Empanadas 5411 quickly followed (that's it in the background of above shot, headed east on Lake).
As of this writing, the Great Food Truck Ralley is to go on for four more hours -- a few places, like Jerk Modern Jamaican Grill -- told me they were ready for many more customers. Jerk serves a find product -- well-seasoned jerk chicken for about 7 bucks -- but we waited in line for 20 plus minutes, and that was before other places started shutting down.
Clearly there is a hunger for this kind of thing in Oak Park. The demand is there. The question is, will Pilgrim seize the opportunity to have similar events that capitalize on the unforeseen enthusiasm for truck-borne chow? For instance, would it not be awesome if there was some way of bringing in food trucks in tandem with the Farmer's Market (maybe after 1PM, when the market is pretty much shut down)? With all the games at Ridgeland Common and the High School Track, I'd think vendors would find it a worthwhile venture. Heck, many vendors came today expecting to sell no more than 200 units – my guess is that most could have sold many, many more than that.
Despite the radical underestimation of attendance, the disappointing sellouts of almost 30% of vendors in first hour, the overcast skies and chill weather, I believe this event has to be considered a success – and I'd hope, a predictor of how well such events would do if they're allowed to continue.