I'm sure it has nothing to do with Walmart offering free 2-day shipping on orders greater than $35, no membership required.... Under $35, no worries, $5.99.
Walmart also has a reputation for shipping things out promptly unlike Amazon. Amazon is fine if you have prime, but if you choose free shipping, there are times you may wait a week for your item to even ship.
Bingo. Walmart also has the best customer service you will find.