It's a design contest for some people's favorite band(s). Not everyone sticks their nose up at doing something they're good at if they aren't also getting paid for it. Maybe some people like the idea that a lot of other fans will be walking around wearing their design, that something they made will become an official part of a band they love. Sure they only get 10 free shirts (plus 2 free tickets to the show). I am sure they'll also get to meet Max easier than the people who wait outside his trailer at shows.

Karl of Museum Mouth is a designer so if they were just looking for someone to design something where they wouldn't have to pay, they could just get him to design the shirt for the tour. This thread is ridiculous.