Good discussion, guys.
My initial point is it is pretty disgusting for a media outlet to take 100% of the proceeds of a "charitable event" in payment for advertising.
Whopper, it is not a commercial/non-commercial thing. In fact, if it can be argued that a broadcaster that is deriving a profit from the public airwaves has a greater responsibility to unpaid public service than a noncommercial outlet.
As for "exclusive" event sponsorships. It sure ain't public service when all you are doing is expecting something directly in return. Second, contractually requiring the charity group to only use your station only benefits the station. Example: this Fall, there was a large community event which required thousands of volunteers. As the week of the event approached, they were still short a couple hundred people and needed to reach more folks. I volunteered our airtime to help recruit additional folks because this is something we do probably better than any other station. The radio sponsor of the event objected because they had the exclusive.
Tell me how that benefits the greater good.