I suspect spring admissions is more motivated by capacity considerations, although schools gaming the rankings may see a small benefit.
USC's is called Trojan Transfer Plan. It is offered to kids with good applications that otherwise would likely get in, but didn't perhaps because they applied to a competitive major/school, so they didn't make the cut freshman year.
WOW -- so the 3.8 is expected of first-semester freshmen taking an engineering core?
That kind of performance is pretty rare, even for a well-prepared kid at community college. And remember that USC is asking this of kids whose HS credentials didn't make the cut. This has to be primarily a way to gently reject legacies or other special groups, not a way to admit sophomores.
Concerning first semester abroad: Do the stats of those students count in to the freshmen class? I thought those students were registered as full time freshmen and not as transfers.