We have our own hens, so fresh eggs are typical at our house, with exception of this time of year when our hens stop laying for a bit.
I was at the grocery store and checking out the eggs. Since I don't usually buy eggs I was surprised at the variety and selection.
I am of the opinion that the brown eggs marketed in the gocery store are dyed brown. The packaged brown eggs are very dark in color, and show the tell tail signs of being colored . As you might see when you dye easter eggs. Uneven color, unnaturally dark color, small blemishes in the shell that don't absorb the dye , glossy finish rather than a natural matte shell.
I think one of 2 senerios applies.
1) maybe mass brown egg production , like in my small coop, produces a variety of shades of brown eggs. So they dye them to look consistent.
2) The eggs are actually white, and they are dyed simply to be packaged and sold as brown. There is probably not an actual law or regulation for over site.
I did some research, and found 2 different people questioning why their brown eggs lost the color when boiled. 2 different egg producers responded. They patronized, saying that boiling eggs with vinegar makes the brown color come off.
That is such crap! The color never disolves when we boil our fresh eggs with vinegar.