Apple stole their trademarked design and then paid $21million for it without years of court battles. It sounds like you're setting this up as a defense of Samsung, but it's a pretty strong argument against.Apple paid out of court before it got there, which they were being threatened with. Doesn't matter if it didn't interfere with the Swiss Railway Company, Apple stole their trademarked design.
Interference with business does matter when calculating damages. SRC had essentially zero lost revenue from their ongoing business-- so if it were a court settlement the $21million, less a reasonable license fee, could be thought of as almost entirely punitive.