Why Amazon keeps adding more benefits to Prime

In the past two weeks, Amazon has added benefit after benefit to Prime. First, the company announced that Prime subscribers, who pay 99 a year for free two-day shipping on a vast selection of Amazon products, would get access to 1,000 free e-books and magazines. Then the Wall Street Journal reported Amazon would develop real-life convenience stores meant to serve its Amazon Fresh customers, who all subscribe to the grocery delivery service for an extra 14.99 a month through Prime. Finally, on Wednesday Amazon launched Amazon Music Unlimited. The streaming service meant to rival Spotify and Apple Music comes with a 2 a month discount for Prime members, undercutting Spotify's 9.99 price with a 7.99 option.