The author of this piece doesn't seem to know much about Amazon's product offerings. Prime is free 2 day shipping along with some free video streaming. Fresh is the Grocery delivery service.
Prime is a subscription you pay in exchange for free shipping from Amazon, and Express is a subscription you pay in exchange for free shipping from Instacart. Offering such a subscription had a positive impact on revenue-per-customer for Amazon, and Instacart may benefit from the same. The author seems to have made a fine analogy to me, and the fact that Amazon also has a separate grocery delivery service is completely tangential to his point.