I am not sure you could really compare them. George was the next heir in line and didn't have much of a choice.
Haendel went to London since there he got payed better. Admittedly, he did so while he was still under a comparatively good contract in Germany. As far as that is concerned, you are right, he doesn't really fit in with the list. But one reason for his emigration was also that he felt he was not appreciated enough in Germany. In London he was #1 while over here he'd only have been some composer at a comperatively small and unimportant local court. While I think we can mostly blame his big ego, to a certain extent he might really have been under-appreciated.
Which brings us back to Ravi Shankar who seems to have had not such a big ego. But he, too, left his home because abroad he found better career chances. And one must not forget that at that time (in the 70s) India was one of the poorest countries in the world, as badly off as many African states. Something that has changed quite a bit in the last 2 decades.