TV is more easily accessible then cinema. You are usually few steps and one click away from turning it on. In order to get to the cinema you have to get to the theatre and pay.
TV is more popular then radio, because you give TV your full attention. Listening to the radio is usually just one of the things you are doing. There is not enough stimuli to keep your attention.
TV shows are also designed in an easily accessible way, where you don't have to think constantly, what message author wanted to deliver, you just consume the content. It doesn't tire you.