Why Do Local News Shows Advertise?

I find it amusing to watch local news shows advertise themselves on TV. Sure, they need ratings like every other show. But come on, it's local news.

• It's all pretty much the same. There's hardly any qualitative difference in the reporting they do. A bit of national and local "hard" news at the beginning, followed by a softer or investigative story, weather, sports, and we're done. The same formula, everywhere.
  
• I don't care how many Doppler radars you have or how many times you do on location live reports. It doesn't make me want to watch one show over another.
• You can get all this news and more, on demand, with video and audio if you choose, on the Internet.

I love it when they tout themselves and their resources, with that triumphant music in the background, as they spring into action to report the latest stories. Lame.