If you are listening to a top 40 station, then of course they will keep playing the same songs over as they are confined to the Billboard top 40. Other stations will constantly play the newest songs from the biggest artists on repeat because that's typically what people want. I really don't think there has to be a conspiracy involved.

If a listener is "seeking" through stations and catch a song they love, they are more likely to stay on the station. The best chance of choosing a song people love is using the most popular songs as often as possible. It's the same exact reason why radio stations try to runs ads at the same time. If a radio station you like starts running ads, but you hear other stations are running ads too, you are more likely to end back at the original station and stay. It's all a numbers game to hook station surfers.

Every movie theater will want to play Disney movies, but that doesn't mean Disney is paying the theaters to play their movies -- in fact, Disney demands theaters to pay far more for their movies than any other movie, but theaters will pay it because they know it will drive people to come and pay for popcorn and other concessions. Same for radio but with ad space. They may pay a lot in marketing to hype people up over a song or movie, that doesn't mean they are paying the theater or the station.