Most, if not all, European airports have international transfer zones, meaning that if you don't have to pass customs and immigration check of the country the airport is located in. On the other hand in US airports do not have international transfer zones. (Note that in case of Schengen zone countries "international" would mean out-of-Schengen).
How about rest of the world, which case is more typical?
Note: I'm not expecting full list of countries, just general indication what's the case in other regions.