Why do eggs in supermarkets come only in white and brown shells?

Eggs that are available in the supermarket shelves are mostly while and brown. While the debate around the fact that which one is better continues, the question is why are they of this colour only and why commonly colourful eggs are not consumed.

Why do eggs in supermarkets come only in white and brown shells?
Eggs that are available in the supermarket shelves are mostly while and brown. While the debate around the fact that which one is better continues, the question is why are they of this colour only and why commonly colourful eggs are not consumed.