Umpires don't eat

Lunches that require a knife and fork. It is hard enough to drive an umpire boat without having to balance the food container and hold a piece of cutlery, let alone two.

Besides by the time such hot fiod gets out to us it is generally cold. 

It's the reason crisps are not popular. One hand to hold the bag, another to eat, who is driving the boat?

Chocolate bars etc can be unwrapped quickly and eaten at leisure, and the colder they are the better they taste.

Apologies to the caterers, its not your fault that it can take a long time to deliver your beautifully prepared food. For the treasurer, it's often a lot cheaper if you prepare rolls, or even purchase sandwiches at a supermarket, and the Umpires will be just as happy.