If you stand and look at a flag flying on a pole it is one way round, go to the other side of the pole and it is reversed!
It's all about about being aestheticlly(?) pleasing and so long as nothing offesnive or inaccurate is written they can put more or less anything on the side of a plane in most parts of the world!
Thinking about it, why don't they then write the letters inversed and in reverse on one side of the a/c?
Tex