The US is larger than Europe and importantly very diverse, a melting pot you could say. You will find people in the South are far more talkative than people in the Northwest. The “Seattle Freeze” is real and I believe that it does not exist to the same extent in the South.

Just pop over the border to Canada from Washington state and they thaw right out!

Also, nit, but Europe has ~2x the population of the States, and definitely more cultural and linguistic diversity.

They all talk or at least understand English. The cultural exchange between Spain and Hungary is much smaller. Or France and Poland. And historical shaping is much different - they did not went through the same dictatorships and same wars.