Why is Mamdani using such an inefficient method to help poor people buy groceries?

“the five stores will cost about $167M over ten years, and the discounted baskets will reach roughly 12,000 households. Spent in other, simpler ways, the same money could deliver discounted food to between 70,000 and 180,000 households”Source: https://gizmowarehouse.org/gizmo/nyc-public-grocery-new-math