US models align with our "average" (western) values. If we outsource thinking by using LLMs, why would we outsource it to an LLM that doesn't have our values encoded in it?
I remember asking Gemini about that one famous 9/11 joke from late Norm MacDonald and it got really iffy about answering. Told it that hey I'm not american and in our culture it's not such a taboo.