This is true in many markets. It makes you wonder if the casual web surfer who scans the 'ratings' with many stations makes advertising decisions on what they see there. After all, incomplete data is still data and it's readily available on the Internet.
If you're making advertising decisions based on the 6+ or 12+ numbers that Arbitron allows the public to see, then you don't know how to evaluate the data.
Of course, when selling direct, the business owner is more apt to buy the station that she or he (plus friends and family) listen to or buy based on community relationships. When you sell direct, you're not selling cost per point.
The people who understand how to read the ratings get the real numbers from Arbitron and not the newspaper.