just how does TiVo obtain and distribute that data?

They buy it from Tribune Media Services. They're one of the standard suppliers of such data.

The TiVo is also capable of knowing if something will be run "offset"... if the data from Tribune is correct. I was browsing with TiVoweb last night on my unit, and I had shows which ran from 2:05 to 2:40 for instance.

It's Tribune's fault that Daily Show never has episode info.