Why are the shells of salted eggs colored red?

The commercial salted eggs are duck eggs and always dyed red to differentiate these from fresh eggs; as these are also packaged, transported and displayed in egg trays used for fresh eggs.

Why are the shells of salted eggs colored red?
In the USA, I thought it is pickled eggs that are colored red. The red is due to beet juice.



The color is just a symbol people use to differentiate the pickled egg from a regular egg.



Also, pickled eggs are typically found in the old-timer bars.
Reply:it's basically just to differentiate it from the usual eggs..that's what i know..
Reply:I think its colored red just to differentiate it with the fresh chicken eggs in the market.
Reply:i think its the "tea" they use or saffron
Reply:to distinguish them from "regular" unsalted eggs.. By the way, just in case you didin't know, true "red" eggs are duck not chinken..