Exactly. But then again the international Box Office was way bigger in 2013 than it was in 2008 or 2010, also MoS had 3D unlike the first two Iron Man films. MoS had the opportunity to bank on a widely known character that had a lot of previous incarnations (wether its in movies or TV) whereas Marvel had to use C-list characters mostly unknown from the general audience, producing films on a much smaller scale with way lower budgets than what WB spent on MoS.
I think the more accurate comparison should be with Guardians of the Galaxy in which the Marvel brand somehow offsets the fact that the characters themselves were mostly unknown. Also you have similar-ish international markets, 3D and PLS.
But aside from raw numbers, the fact that no Marvel film yet, in the 11 film they released (so that's plenty of opportunities to fail) displayed a multiplier as weak as MoS. And in general their "origin stories" all held a whole lot better.