why waste enormous sums of money on premises and other costs when they could just start food banks
This runs into the problem of charity out-competing potential business ventures. Government subsidized private groceries, or public-private partnerships or just plain government run grocery stores can alleviate the problem of a food desert while still bringing the benefits of an active business to the area. The local government can increase or reduce its investment as needed, and it doesn’t create a service that inherently can’t be competed with by private business in a space that’s already unprofitable/too risky to operate a business within