Cadillac, BMW, Mercedes (their respective premium and high-end models). You don't care what's in your run-of-the-mill C-class, but the factory fill for an AMG vehicle is of more interest.
And then there is Rolls Royce, Bentley, McLaren Ferrari, etc, all very expensive vehicles. This is where lubricant manufacturers like to truly promote their factory fill. Because if Shell Helix Ultra works great in a Ferrari, it should do well in a Hyundai as well, right? Or you might care that Bentley uses Castrol as their factory fill, because then it'll do great in your Avalon. Silly examples, I know, but that's kind of the point of marketing.
Rich cuatomers of some of these vehicles will never care what lube runs in the engine, unless they're car enthusiasts.