No Safety Nets
In the U.S., if you get fired from your job, that often means immediately being out of an income and health insurance as well. This is not how things work in many European countries, where people who are fired from their jobs are frequently entitled to 3 months salary in order to provide a safety net until they can secure a new job.
Social Lubricant
In the U.S., small talk is very common and is often expected of you. This is not the case in Europe, which means a lot of non-American visitors feel that they must become a more extroverted version of themselves when they are in the United States. Europeans are often confused when Americans ask them how they are, when in fact, they don’t really care and are expecting the typical “fine, how are you?” response.