The article overstates the use of ML at least in fulfillment we use a lot of math models (eg xpress solver) and optimization algorithms (traveling salesmen type problems) but not so much in the ML space.
Usually optimization takes forecasts as part of inputs. It is actually a lot like reinforcement learning, where the sales forecasts are part of the environment. This is standard process for supply-chain management, not just retail industry or at Amazon.
My team does ML in Fulfillment. Search my username on phone tool to figure out my team.