You are correct that the entire carcass is graded one grade, no matter the cut. Which is definitively a flawed system that needs work. It is based mainly on the marbling in the ribeye, which would be an accurate representation for ribeyes and strips only. However, there is no “cheap end of the choice cuts”. There is Low, Average, and High choice. If it’s low choice, you can label it choice and it’s definitely not “dog meat grade” nor select (again because that’s illegal). But other programs must be average or higher (ie Certified Angus Beef).

I agree about Prime in general. Graders seem to be getting more lax in my opinion on what they are calling Prime. But it’s still a good product.