I'm not so sure people in Europe are better off. There are a lot of very poor regions in Europe compared to how people tend to imagine Europe. In fact, most European countries, if they were U.S. states, would rank among the poorer U.S. states.

Now, looking only at the statistics, there are certainly some things European countries are doing better than the U.S. But based on my research so far, which admittedly isn't enough for a full understanding, my tentative conclusion is that almost all of those things don't seem related to economic policy. They seem more related to things like urban planning, for example more pedestrian- and bike-friendly cities.

In terms of work and wages, U.S. wages are substantially higher than wages in most European countries. And I'm not just talking about longer hours. I mean the compensation per hour is significantly higher.

EU Europe average per-capita income ≈ $30,500

United States per-capita income ≈ $68,000

Averages tell nothing about an average citizen.

Also, there are other measurements like inequality, healthcare cost, social securities...

Averages tell us the general availability of wealth. To give you some perspective, most European countries are poorer than the poorest U.S. state, which is Mississippi. There just aren't as many high-paying jobs. And these figures encompass everything, including what the government spends on health care and welfare programs and education. So Europeans as a whole get much less per capita from both government and private sector. When it comes to purchasing power parity, which takes into account cost-of-living differences, the gap isn't as big as above, but it's still pretty significant.

Avetage tells nothing you should use median or a graph.

Median data is better, yes, but it's harder to get. Average correlates quite strongly with median.