Prime has always and will always be all about fast shipping. Members living in the continental United States (and in many other countries) get free two-day shipping (order on Monday, guaranteed by Wednesday, e.g.) on countless Prime products. In some zip codes, orders over $35 can even get same-day delivery.
And if you don't need that Emeril Lagasse air fryer or Bluetooth headphones delivered within two days, you can earn rewards that will apply to future orders by opting for no-rush shipping. Wait five or six days, earn future savings; not a bad deal, really.
(On the other hand, if you live in certain areas, you might have to wait as little as two hours for your shipment thanks to Prime Now.)