It would be nice if every story was clear cut. But this one definitely isn't. The place that sold the turf was not the same place that installed it. So there's no way of knowing if all the weeds were killed before hand. That's why I can't nail some turf company for selling bad grass. The company might have - but there are just too many variables to know for sure.
But I still feel the homeowner has an important story. She had no idea (and neither did I before today) that there's such a thing as "certified" grass. I'm told it will cost 2-3 cents more per square foot - so a couple hundred dollars more for a typical yard. But in my opinion, it would be well worth it. The fields are inspected and so is the grass - and they guarantee the grass you get is the grass you want.
OSU, Oklahoma Cooperative Extension Service, put out a directory that shows who produces which types of sod:
The Oklahoma Crop Improvement also has a website that may be of help. This link will take you to their list of grasses that are certified here in Oklahoma:
Also, the National Turf Grass Evaluation Program has done studies in Oklahoma to show which grass does best here. I've put a link to their "Oklahoma" site. It's a bit technical, but if you want to see how your grass rates, check it out: