I believe that in many cases they are.

http://www.macalester.edu/courses/geog261/Brown_Seoul/images...

Drive around a modern city in Asia and you'll likely see kilometer after kilometer of cookie cutter apartment buildings, with building plans so simple, they could almost be replaced with stacks of cargo containers and a central elevator shaft.

I may be wrong, but I'd be highly surprised if there wasn't a tremendous amount of prefab on display here.