I think they are omitting yellow flags because fans hate the constant restarts and drivers totally abuse it.

Chris Morrow deserves a medal for what Walter's did to him in the feature, talk about sportsman he took his lick and swung back around and continued racing.  No yellow flag for him.  If that was Walters he would have stayed there and created a caution.

Just one example why the yellow isn't always necessary and how it gets abused.

i believe there was this kind of abuse saturday. i saw a car stop in corners 1 and 2, give some fans the finger, the yellow came out and he drove away. I AM NOT 100% SURE IF IT WAS INTENTIONAL OR HE JUST COULDNT GET GOING! (just wanted to make that clear.) but the only thing i dont get the #2 TC was stopped, not completely on the track, but on the yellow lines he sat there for like 2 or 3 laps, if im not mistaken. then they finally brought out the yellow.  once again nothing against sunset, maybe im used to barrie bringing out the caution lots. feel free to correct me.