What may be true is that UK recipes have more fat in them than US ones, which would decrease the ratio of flour to fat... we have a thing about fat in the US.
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For what it's worth, the Cook's Illustrated yellow cake recipe has the same ratio of butter to flour as the recipe given above, although it has a more sugar, as well as milk and vanilla. (I'm not sure that what EoS is describing is QUITE yellow cake, which would have vanilla and generally milk in it, and so presumably would be a little moister.) Cooks Illustrated does NOT have a thing about fat.
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Cinnamon rolls are typically made with something closer to bread dough, which is always going to have a lot more flour than a yellow cake.