Zaugs (and any other service) is likely constrained by speed of service needs. Serving 75,000 people lunch in a two hour window generally means they are batch cooking food, keeping it warm, and selling the same basic 2-3 meals to everyone who walks up. Unless you're willing to pay twice the price and/or wait forever, fresh food and food customization (ala Subway) are probably not gonna happen at an event like Airventure.
I buy a jar of peanut butter and a loaf of bread and eat lunch all week for ~$10 without eating fried food or standing in line. That way, I don't feel as much guilt when I have Brats and beer for dinner at SOS Brothers every night.