Amazon made a bet that customers would not revolt in mass when it shifted its video strategy to make its entire customer base default to an ad-free video service. The move was Netflix-like in that it established the service as the largest ad-supported service overnight much the same way Netflix became the largest streaming service in the world by offering it to customers who were already paying for mail-in DVDs at the time. Amazon is seeing that bet pay off.
How did they do it? By limiting the number and when ads show up in content. While there may have been a very negative reaction had the service added 20 minutes of advertising like normal network TV shows do, as it is Amazon has seen very little churn in its subscribers according to Hub Research.
Will other services follow the pattern? Give it a little more time and we will find out.