I will agree that Kathys birds really look like Dels to me when compared to hatchery. I would think that since Hatcheries are interested in selling chicks they would need great layers so they would only use birds that are sure to lay well. Which in perpetuating their lines would be increased over time. Since that would be the most important trait others would fall by the way side.
We should get beyond the idea that hatcheries are selecting for the best layers intelligently. That is simply not the case. They simply breed replacements from pullets. All in and all out. It is not as if they are trap nesting their birds or something. They do produce the truly commercial lines. They simply purchase the eggs from the actual breeders of the truly commercial production birds. That does not include our Standard breeds. All that is a required by them is a general color pattern and eggs.