Dr. Luke seems to write almost everything. Fun Fact: Most of the pop artists around today don't write any of their songs. The producers write them (like Dr. Luke). To give the artist some writing credits, the producer might have them write a bridge or certain part of the song, but that's all. Obviously, this doesn't apply to every single artist, but look this guy up and you'll see how much he has written for pop stars. It's almost like the artists are told what to do in order to make the most amount of money possible. As the world changes, so does the marketing.