Just some thoughts I have. I could very well be wrong and encourage others to disagree and straighten me out.
Once the hair and skin are off, there can't be any exterior color bias applied to the carcass, It gets graded like any other carcass. So, those who are able to retain ownership through the feedlot are much more likely to eliminate any color bias impact and get paid for the value of the carcass. If you go that route, there are a lot of things to worry about other than color. If you sell at an auction, the bias is present not due to any conspiracy - but due to supply and demand. A free market economy. If you look at the ownership after weaning, the calf might be purchased by a stocker operation who later sells to a feedlot who later sells to a packer. At each point of ownership changes, the seller hopes to sell as high as possible, but the buyer hopes to buy as low as possible. With price determined by supply and demand. There are probably buyers involved who have orders to buy certain quantities of animals of a certain type. And they are buying for multiple people. The buyer is trying to fill the order he has been given as close as possible based on what the new owner wants for his conditions and his experience with types of cattle and his belief about relationship between breed composition (real or perceived) and appearance as relates to the new owner being able to make a profit off the cattle. Many issues here including beliefs/experience about health, growth, cost of gain, carcass quality, frame, appearance, making a load of similar cattle, weather/environment where they are going, etc. These issues occur each time ownership is transferred and maybe the evaluation of worth is a little less biased as it moves though the supply chain. Point of my rambling - the cow-calf guy is the bottom of the supply chain and can be rewarded for matching his supply to fit the demand in his marketplace.
Now, it seems that this color thing is much more pronounced in the US than other countries and more so in some regions of the US than others. Anyone have opinions on why that is the case? But, I still think it is just supply and demand.
Hog and chicken production pretty much eliminated this with their meat due to going to a narrow genetic line (they are all white and efficient) with most animals owned by a few companies.