They even have a fancy set-up manual for the broiler parents. Look up Ross 308 parent stock manual. (can't paste a .pdf link from tablet)
Each Cornish X strain is a bit different in its management.
These manuals are for large-scale farmers who have invested tens of thousands of dollars in a climate-controlled broiler house. They then order either broiler chicks or parent stock from the large firm.
This is a very different model from free-range, partial free-range, Label Rouge, or tractors.
However, some techniques like weighing the birds at different ages, are similar.
I happen to be in an area where there is actually a taste preference for non-CornishX chicken. For example, around Christmas, people will actually pay $14-15 for a mature rooster (RIR or BR mix - nothing unusual) for eating purposes.
Marketing is more than half the battle in trying to make money from meat chickens.