If you mean median or average, both actually. You have to quite poor to be worse off (on average) in the US than in Europe (don't know about Japan); last time I checked it was something like the 10-20th percentile. FWIW, I am European, so no bias.
If one takes into account the social services (education, healthcare, etc.) and general worker protections (mandatory PTO, parental leave, etc.) I think it’s clear the median earner in Western Europe is doing better than the median US worker in quality of life terms.
The median net worth seems to be higher in Western/Northern Europe than the US though. Eastern Europe pulls down the statistics quite a bit. Canada also has a higher median.
https://en.m.wikipedia.org/wiki/File:World_map_of_median_wea...