As you might expect, most of the food vendors are real characters.
It's commonly believed that the Yakuza are involved in the assignment of choice spots at major festivals.
The vendors themselves are certainly not Yakuza. However, it's a profession where you need some ties to the Japanese underworld. Rumor is that the festival food business is very lucrative. It makes sense — access to millions of hungry customers. The vendors don't need to invest in expensive real estate or equipment. Prices are slightly inflated too.
The vendors are usually friendly and take pride in their food.
It must be a tough life moving around from festival to festival — setting up and tearing down. Serving long lines of drunk customers.
At most festivals the food vendors are part of the attraction. There's an atmosphere about festival food stalls. Japanese festivals wouldn't be the same without them.