Radio advertising is something that unlike newspaper advertising, hasn’t really seen the same level of competition from the online world. And in keeping tune to this reality, radio advertising has not held as strong of a hold on radio listeners as it once had.
As this report indicates, tracking and maintaining a strong foothold in a media that Google has very little experience in was just not in the cards for the search giant. In the end, I guess it was meant for Google to lose out on this one.
Google discovered later on that there is a human side to radio advertising that no amount of automating will help with. Due to this, Google was later forced to withdrawal their radio advertising efforts as clearly, it was not meeting with the level of success that they have hoped.