Most U.S. radio stations fail because they don't understand how to build up an audience in the new online digital age. There are three reasons for this.
First, most stations follow the traditional path of playing top 40 music and taking what they consider to be a passive approach to getting more listeners. Following this approach means that they are unwilling to take risks or try new things that could attract more listeners.
Second, most stations hire inexperienced people who don't know what they are doing and don't really care.
Finally, most stations rely on old-fashioned commercial considerations like playing music that is popular and sponsorships from local businesses to attract listeners. They don't understand how to use the range of new media platforms – including internet radio – that people now use to find and listen to music.