Nobody likes duck eggs in my home

My daughter is only two years old but she can easily tell it's not chicken eggs. Not like it.
Duck eggs are harder, and it's quite salty after preserving.
My husband is not digging into preserved duck eggs either. I bought it once from Korean grocery.
Their question is"why duck eggs are so hard and salty?"
Mommy is weird to choose salty tasting duck eggs, conclusion drawn.