Nutritional information for Steak and Shake:
https://www.nutritionix.com/steak-n-shake/menu/premium?desktop=
I don't see exactly where their website says grass fed beef only - but they do specify restrictions.
https://www.steaknshake.com/selective-about-the-food-we-serve/
However - if you compare fast food shops, Steak-n-Shake is moving in the right direction!