The shows use something called 'prep burger' which is prerecorded or prewritten comedy bits that multiple stations reuse, such as fake prank calls (real ones are illegal now). They buy access to a database of them and shameless reuse comedy bits with zero originality.
It's like mainstream pop music, the corporations have focus-grouped all the creativity out of the shows and keep everything within the safe confines of control and management. And I won't even get into their obsession for political correctness.
The days of Howard Stern or Opie and Anthony style talk shows are gone. Even XM Satelite radio talk shows have all been neutered.
This is why podcasts are new and interesting. The personailities are free to do and say whatever they want. They dont have management or producers telling them what audiences want to hear. So they create authentic and original content.