Maybe its to prevent "dumping" from foreign companies, and protect South African company's. By dumping I mean when foreign companies over produce certain goods and then they try to sell off the surplus in South Africa, they sell it for cheap, just so they don't make a huge loss. This is obviously not good for local companies and by letting the foreign companies list on these price comparison sites, then they are just being granted easy access to South African consumers so as to dump their surplus.