<human>: Can you give me a shortened version of the text?

I am part of a group of four 19-20 year old university students helping to build an open-air community filter factory in rural South Africa. The four of us are middle class Americans here on a research grant, and the factory is being paid for by a nonprofit affiliated with our university.

We have paid a builder to construct the office, and 2-3 other guys around 30 years old often help out during the day.

We arrive around 8:30AM so are hungry for lunch around 12PM. We normally bring the basic ingredients for PB&J with us and drive to a nearby gas station to eat the sandwiches. We do this because sharing is a strong cultural value they have here, especially with food. Until now, our gas station trips haven't been a big deal.

The first day, the workers asked us to bring lunch for them the next day. Realizing that would set a precedent, we contacted our community partner, who told us we didn't need to do that since it was not our job to provide them with food.

Today (1 week in, 3 weeks left), we didn't have much work since the materials had not arrived for construction. When one of us told the guys that we were going to the gas station for lunch, one of them tried to come with us and another asked us to buy them a loaf of bread. We felt terrible declining both of them and were quite awkward about the whole situation.

How should we tell them that we are taking our lunch break on days when there is no work to do? Is it unethical to not provide them with cheap lunch ingredients (some of the men are volunteers and get paid nothing for their labor)? We feel that we are already providing a lot for them in helping to build the filter factory and paying for all of its construction. Are we obligated to do these other small  tasks for them? Any suggestions on our situation would greatly be appreciated.
<bot>: Helping build an open air filter factory in South Africa and the workers are asking for small favors. Are we obligated to fulfill their wishes?