That's because in America we're so concerned about contaminants on shells that we clean all the protection off the outside, making the shells porous enough for bacteria to get through. Store-bought eggs in the US so have to be refrigerated.
This is because of a difference in food safety standards. When eggs are laid, they’re covered in something called bloom. It’s a slimy coating which the chicken produces. It’s full of good bacteria, and it protects the eggs and prevents them from spoiling. So Europeans buy eggs with the bloom on them, and don’t need to refrigerate their eggs.
But in America, the Food and Drug Administration has strict regulations regarding animal poop near food. Namely, you can’t have animal poop near your food. Full stop, with very few exceptions. And since chickens poop out of the same hole they lay eggs from, part of the bloom is, in fact, chicken poop. So eggs in America have to be washed, to remove that chicken poop before they can be sold. But this also removes the bloom, meaning the eggs are unprotected and need to be refrigerated.
Bloom it up! Local farm stands have a good bet of being unwashed eggs. Can't say I blame the FDA on this, given the awful state of dairy and chicken farms that we get these eggs from...
It’s dry by the time it reaches you, but is still protecting the eggs by filling in all the pores in the eggshell. Basically, eggs in america have porous shells, which means they spoil faster in the open air.
Longer! In Scotland, mostly cool, mine sit on the counter for a couple of months at a time.
I spin them to check if they're still okay. You spin them on the counter, briefly place a finger to stop them and release. If the yolk is still fluid the egg will start to spin again, and they're good to use. If the inners have congealed they stop dead, and go in the bin.
Eggs that have been washed (i.e. had the cuticle remove) should generally be stored in the fridge or used very quickly. Eggs in either case shouldn't generally be moved from refrigerated storage to the counter unless they're going to be used very quickly because the condensation can do bad things.
I was told that they last the longest if kept out of the fridge the first week or so and afterwards you should put them in a fridge. And for some reason if they are already refrigerated they need to stay refrigerated no matter how old. No idea if there is a scientific basis to it, but it sounds at least plausible that there is.
And for some reason if they are already refrigerated they need to stay refrigerated no matter how old.
It has to do with washing. Eggs, fresh from a chicken's poophole, have a protective layer around them that allows you to store them at room temperature. If you wash them though, the protective layer disappears and the egg shell becomes porous, and as a result you need to refrigerate them. If you buy eggs that are already refrigerated, they are likely refrigerated because they have been washed, so you should keep them refrigerated as well.