how is that not in the spirit of wartime cooperation? with spirited cooperation, each side contributes in order to get what they want from cooperation
if you want more nuance, the American administration, completely upper class https://oldlifemagazine.com/look-magazine-april-12-1949-fran... was 100% behind helping the UK and got the job done, but we have a political system that has to respond to the common people, and just as the English labour party has never thought "oh, what can we do to help the US?", neither has the American populace in reverse, on top of the traditional American individualism and revulsion toward European monarchical and imperial wars.
Difference is, we don't bitch about it.
Britain is completely entitled to be proud of its absolute grit, prowess, and determination wrt the second world war, but the US did right by them too. America was already on the rise, but not entirely self-confident (that had begun wrt WWI but had not become a birthright till after WWII.) We didn't have a 19th century empire that collapsed (although we were in certain respects a self-contained 19th century western empire), and we were perfectly positioned (geography, population, GDP, English Common Law legal system plus bill of rights, but lacking other tired old ideas about class) to assume the mantles not only of British hegemony, but also French, German, Dutch, Belgian and the other "imperial thrones" that were now unoccupied. it was to our benefit but it was not "our fault" or even "our doing"