On the simplest level conservatives are happy people who enjoy the stimulus of people talking to them about a wide range of ideas. The more complex the ideas the more interesting and convivial the conversation.
Comedians on the other hand help lighten the burden of unhappiness that sits on the shoulders of most Lefties.
A more complex explanation is that the conservative world is made up of many different clusters of ideas ranging from social issues where the status quo and tradition are important to parts of difficult moral issues and commercial issues where trade, business and regulatory issues present complex problems. That complex environment creates a world in which an interesting radio voice can make comments and arguments interesting enough to fill three hours a day and five days a week with very little staff support.
Comedians on TV deal with almost the exact opposite. The Lefty orthodox line is published almost daily in the New York Times, the Huffington Post and the Doonesbury cartoon strip. Therefore comedians have common enemies and simple themes about which to construct jokes. Their staff begins each meeting with a set of enemies, pre-ordained policy positions and an audience that will always agree with the underlying ideology.
That is why talk radio is conservative and comedy TV is Lefty.