The ranking calculation does take into account the importance of the match and regional strength.
The relevant factors are:
Friendly match x 1.00
World Cup preliminary match x 1.50
UEFA x 1.00
CONMEBOL x 0.99
CONCACAF x 0.94
So even though these are just a couple of the factors that are used in the full calculation, its clear that FIFA do take into account that CONCACAF is weaker than UEFA and South America. And personally, I think European teams have an advantage over South American teams in rankings, because there are far more $h!t teams in Europe to blowout than in South America.
USA would have actually gotten more points for their match against us because the match actually meant something. Argentina would have easily held on for the 2-1 victory against England if that match had been in an official tournament, so England have nothing to complan about.