They often end up with bits of stuff stuck to them while they’re wet, like feathers, bedding, etc. Poop isn’t uncommon either. The same people who won’t buy salmon unless it has that freshly dyed pink color, and won’t buy potatoes if they aren’t universally convex, balk at the bits that remind them they come from a real place and aren’t just summoned into existence for their sake. Washing the eggs takes off the bits but also the ‘bloom’ which is the natural barrier to bacteria and the like. Hence, refrigeration.

Because the conditions that the chickens are raised in promote growth of salmonella to such a degree that they need to chlorinate the outside and scrub & wash away the cuticle. The production model for chickens is so harsh that they can’t keep themselves clean or care for themselves. And the chemical companies profit off the model so there is no incentive to make chickens happier or healthier.

Because it came out of a chicken’s but. Don’t you wash your turds before you eat them? Jk, there’s no good reason to do so.