Costco Wholesale and Target both reported year-over-year decreases in e-commerce sales in their most recent quarterly reports, and many smaller e-commerce companies are in the same boat. Amazon, the indomitable king of e-commerce, has been struggling with too much infrastructure, slowing sales growth, and high pandemic-fueled growth that's harder to build on now. It operates a business-to-business platform offering cross-border solutions for online retailers.