As someone who worked in Amazon's supply chain, I'd have to say that WalMart anecdotally smashed us with their planning and buying technology. They had an entire system of weather-based inventory adjustments. I've heard stories of inventory being pulled off of shelves in the midwest to reroute to Florida a week in advance of a hurricane, well before the local authorities had even issuing weather alerts. I'm talking batteries, water, prepackaged foods, etc. Their planning systems are pretty magnificent.

The whole customer experience for Amazon so much better though. It's definitely not perfect, but we went through a lot of trouble to be as accurate and upfront about delivery expectations, prices, alternative products, accurate reviews, etc. Walmart still has a ways to catch up on the customer side.