No one was saying to compare singular European countries vs USA.
We were saying that the rest of Europe should be added (EU =! All Europe) as well as adding the rest of North America (and possibly South, but then that would be 2 continents versus singular continents)
In truth the order is probably like this:
Europe>N.America>Asia>>>>>>>Oceania>S.America>>Africa>>>Antarctica (included for completeness)
S.America might be higher than Oceania in monetary terms, but I suspect most of S.Americas sales are counted in N.America as consoles take a long time to release there officially