Americans just like to refrigerate everything, that's why our fridges are gi-normous!
I had this discussion with my English husband when I complained about there not being a refrigerator where I worked, so if I brought food to work it would be unrefrigerated since the morning. (Not about eggs, but about food in general.)
My ex was a cook and had to spend many hours studying how food poisoning occurs and what temperatures are optimal for bacteria growth.
Here is an article from the Center for Disease Control, which states that eggs are safest when stored in the fridge. It is a US government organisation, though, and it only refers to the prevalence of salmonella in parts of the US, so maybe it just isn't a problem in Britain?
Also, there are parts of the US where it gets much warmer than in the UK, so it's possible that in the UK they just don't have to deal with the kind of food spoilage you could get on days when its 40 degrees C and 99 percent humidity.