Eggs are refrigerated at home and sit on a warm shelf in the shop here, which one is wrong?

Neither is wrong. They are two coherent systems that solve the same problem in opposite ways, and the difference comes down to washing.

An egg comes out of the hen with a thin natural coating on the shell, the cuticle or bloom. It seals the pores and is a genuine barrier against bacteria getting in.

In some countries, eggs are washed and sanitised before sale. That removes surface contamination and it also removes the cuticle. Without it the shell is porous, so the egg must then be kept refrigerated for the rest of its life to stop anything getting in and multiplying.

In others, eggs are not washed, so the cuticle stays intact and the egg is safe at room temperature for a reasonable period. Instead of washing, those systems typically focus on preventing contamination at the source: flock vaccination and controls on the farm.

So one approach cleans the outside and then needs the cold chain. The other keeps the barrier and needs healthy flocks. Both work; they are just not interchangeable, which is why each looks reckless from inside the other.

That is also why the packaging advice differs by country, and why following the advice printed on the box you actually bought is the correct answer.

Both work. Neither is wrong. That is a surprisingly rare answer to a question like this.

The one rule that matters practically, and it is the thing people get wrong when they move: once an egg has been refrigerated, keep it refrigerated.

A cold egg brought into a warm room condenses moisture on the shell, and moisture on a porous shell helps anything on the outside get in. So moving between systems is the risky direction, not either system on its own.

Which gives you a simple rule for where you are now:

Bought from a warm shelf, a cool cupboard is fine, and so is the fridge, as long as you then keep them there. Do not move them back and forth.

Bought chilled, fridge, always.

A few other practical bits:

Do not wash eggs at home in a country where they are sold unwashed. You would remove the coating and get the downsides of both systems. Wipe visible dirt off dry, and wash your hands after handling.

Store them away from strong smells, since shells are porous either way.

Room temperature eggs are better for baking, which is a genuine advantage of the unwashed system and why many recipes tell you to take eggs out an hour beforehand.

And the float test still works in both: an egg that floats is old.

Worth adding why the two systems diverged, because it is not arbitrary and it explains why neither is likely to change.

Both are aimed at the same organism, and they intervene at different points. One assumes contamination will happen and removes it at the end of the chain, accepting the loss of the natural barrier and compensating with refrigeration. The other tries to prevent the hens carrying it in the first place and leaves the egg alone.

Each has a real cost. Washing requires an unbroken cold chain from packing to your fridge, and any break in it is a genuine problem. The other approach depends on flock health measures being maintained, and it is less forgiving if they are not.

There is a practical consequence for shelf life, too: unwashed room-temperature eggs are generally sold with a shorter recommended period than refrigerated ones, and dates on the box reflect the system they were produced under. So do not apply the dates you are used to from one country to eggs bought in the other.

And if you keep hens yourself: what you have is an unwashed egg with its cuticle intact, whichever country you are in, and the room-temperature rules apply - until you wash it, at which point they do not.