I don’t get this at all. If we treat a group as fairly as possible and on average they perform worse than other groups, is that evidence of discrimination? Is there a hypothesis that they need to perform equally as well.?
The other, much more reasonable explanation, is that these differences are explained by the fact that lower-caste Indians are actually _not_ treated "as fairly as possible" by society.
At the individual level exceptions exist, but when you scale out to sufficiently large populations there aren't random demographics that magically perform worse than everyone else because they're all lazy bums.
Becuase I do not believe an Indian's caste affects their inherent ability to perform IT work. If you do believe that to be true, of course you should expect a difference even in a perfectly fair society.
> Can't some groups perform worse than others by random chance?
This is extremely unlikely once you get to higher sample sizes: https://en.wikipedia.org/wiki/Law_of_large_numbers
> Are there really no other factors besides discrimination that could cause this?
Well of course there are. For example, if one group is more educated than the other they're going to perform better.
I made it sound as easy as "just see if the numbers don't match up", but in real life the statisticians that do these kinds of analysis account for other factors that could impact performance, so that if there is a difference it's purely "because" of the caste.