There is also a difference in the quality of life. Most of the clientele seem to be daily wage laborers, who could certainly use all the energy they could get.
But you are correct that it can go either way. I'm glad that lentils, at least, are part of the menu. And as someone living in the US, the meals offered seem like luxury compared with the crap fast food meal that seem to be the staple of lower class Americans (please, its not a Nationalist thing. American fast food is objectively bad for health).
This isn't exactly your 80 rupees/dosa Darshini.
Of course the food quality won't be all that great. Thats also with children's mid day meal program in Government schools.
The base rule for things like this is something is better than going hungry.
Depends on how it's made. Oil/butter is often added because it's cheap and provides "fullness" without being nutritionally satisfying. With food this cheap, you'll need to take a close look at what's actually going in the food.