Apple's terms of service are required of them by the content owners who will not allow cross-border sales. These same terms are common to all legal download stores that carry material from the major content owners. From
This Business of Music (10th Edition) (by M. William Krasilovsky and Sydney Shemel) (and thanks to the Mimico Kid for the reference) :
The difficulty of establishing workable business models for digital files (...) extends to where they are sold and where they are played. This is the issue of territoriality, and it is an illustration of how the Internet makes it necessary to reexamine basic assumptions that have been taken for granted (...).
(....) In the music business the primary problem is that copyrights are national and therefore specific rights are tied to national laws and the interpretations of national courts.
(.... T)hough we can one day hope to see the development of common standards with respect to copyright, the fact that the music business is building upon a history of nation-specific contractual relationships means that the goal of universal international standards is not, for the forseeable future, a practical one.
(...) Adding to the difficulty (...) the copyrights themselves may have been assigned to different companies in different territories. The best hope for a cleaner start and a simpler future is worldwide recognition that digital uses are in fact - and should be in law - totally new.
The content owners don't like cross-border sales of CDs and DVDs either, but there's nothing they can do to stop such sales. They can, though, and do stop cross-border download sales, since if the download stores refuse, the rights holders won't license the tracks to that store.
So unless and until the record companies, et. al, all get together and agree to allow download stores to sell cross-border, there's absolutely nothing Apple or any other download store can do.