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I wouldn't say it really has all that much to do with preference, I think it's more about conditioning. Grocery stores sell mostly white eggs here. Most commercial laying flocks are comprised of leghorns that have been bred to lay lots and lots of large white eggs. At one time, I believe there was a preference for white. But, since leghorns are prolific layers and economical eaters, it's in the best interest of commercial producers to promote white eggs. I don't believe I've ever seen an advertisement that used brown eggs. If I have, they are few and far between. I think a lot of folks go with what is familiar and that, at least for the time being, is white. Also, I know of a lot of people who are simply adverse to food that was not produced in the commercial setting. I guess they think that the regulation makes cleaner, safer food (I most definitely do not agree). 
As a child, I decided that I liked brown eggs best. I thought they tasted better. It wasn't until I was older that I understood that it was just that they came from a better source. The same is true of milk in my experience. We've gotten so used to grain-fed, homogenize, pasteurized milk that most folks are put off by the real thing. I love it when spring rolls around and new grass shoots up and the cows get into the wild garlic...that's just me though.