Lore said it will be cheaper for the company to do next-day delivery versus two-day service because eligible items will come from a single fulfillment center located closest to the customer. This means orders will ship in one box, or in as few boxes as possible, unlike two-day deliveries that come in multiple boxes from multiple locations. Walmart is also trying to limit costs by tailoring products based on what shoppers demand in the local markets. For example, sunscreen would be available all year for areas such as Southern California and Phoenix.

Source: Los Angeles Times May 14, 2019 20:48 UTC