Having flown in both Europe and the US, I can suggest a possible explanation.
In Europe, there is the expectation that R/T is being carried out in a foreign language: English is not the native tongue for most Europeans. To alleviate this, a common phraseology has been adopted. This common phraseology has a small vocabulary, to keep it as simple as possible.
The US situation is different. As the majority (still around 80% I believe, although the number is decreasing) of world aviation happens within the US, most voices you hear on the R/T within US airspace are native speakers of English. There is not the same requirement for strict phrasing.
No one gets R/T right the first try, and Yank-bashing will not encourage visiting aircrew to learn...