A missions trip is definitely meant to impact the students. Mainly in that it allows the leaders and the students to have more time with each other and shared experiences so that those relationships can improve. To some extent the leaders consider the students their mission field.
Sometimes a mission trip has a huge positive impact, and other times you end up inconveniencing the very people you intended to help. I think the key thing is listening to what the people actually need. I’ve heard that “When Helping Hurts” is any excellent book on this topic, though I have yet to read it.
Also I’m not sure about mission’s tortillas, but their tortilla chips are delicious.