Broadcasters are already burdened with price controls on political advertising. The amount of work required to protect a TV station's income stream in the months prior to political seasons is phenomenal.
A station must be extremely careful not to accidentally schedule a low dollar client - or zero dollar bonus spots for the higher paying clients - in large revenue generating time periods.
If you let Mom & Pop in for $50, or 'super-size' Toyota's buy with a free spot, McCain gets the same rate when he comes calling.
Then there's the blanket two hours of political coverage per week. Rule #1 in TV: All markets are different. In some markets, especially the big ones, there are dozens of politicians fighting for air time. Some smaller markets, may not even be as big as a congressional district. Is it fair to make Ottumwa, Iowa AND New York City dedicate the same amount of time each to political coverage?
TV stations don't have the same liberty as radio stations when it comes to commercial inventory. A radio station can create room for more commercials by simply deleting one song per hour. That's not the case in TV. The amount of commercial time available is determined by the programming (except for local news, which CAN be easily manipulated for inventory purposes) If you get six minutes of time in FRIENDS, you get six minutes. You can't delete part of the show to make room for the politicians.
Free political ads would also take away slots that paid advertisers might have reserved - and in the political season, they would take away most, if not all of the TV stations inventory. These free spots would flood the airwaves beyond the levels they now occupy, displacing paying customers - who also have the right to buy advertising when they want and where they want.
There's a first amendment right no one talks about - perhaps Sears could sue McCain for violation of their rights as an advertiser?