its all to do with the company acting as SEAT's importers for a particular country. if the importer wants to list all SEAT Spain's accessories, they can. unfortunately SEAT UK only bring in a small range of what is available although in fairness a lot of stuff is lhd so not suitable here anyway.
the importer can also source their own products and ask SEAT to extend the car warranty to cover these 'importer approved' items. SEAT Ireland actually offer remaps which SEAT cover under warranty.