1) Monopoly - If they can get enough lock-in on customers, they can outlast their competitors and then eventually move the prices up without losing customers (since there would be few viable alternatives).
2) Economies of Scale - In many businesses, the marginal cost does go down once you scale up significantly. They probably expected to cut the cost of food production significantly with volume pricing on raw materials and perhaps more automation of the cooking processes.
I think all of these services understand that this is a low margin business so you have to make up for it in high volume and short term losses are acceptable if you will win out eventually and increase the margins.
