Do eggs actually need to be refrigerated?

The confusing international split has a clean explanation, and it comes down to washing. In the US, commercial eggs are washed and sanitized, which removes the cuticle, a natural coating that seals the shell's pores against bacteria. Stripped of that barrier, American eggs must be refrigerated to stay safe, and once cold they should stay cold, since sweating at room temperature can pull contamination through the shell. This is why your US carton says keep refrigerated and means it.

Much of Europe does the opposite: eggs are not washed, the protective cuticle stays intact, and hens are often vaccinated against Salmonella, so eggs sit safely at room temperature on store shelves and countertops. Neither system is wrong; they are two coherent answers to the same problem. The practical rules for Americans: refrigerate your eggs, do not leave them out more than two hours, and a fresh egg sinks and lies flat in water while an old one stands up or floats as its air cell grows, a genuinely useful freshness test, though floating means old, not necessarily unsafe.