- language barrier
- culture barrier
- thousand mile separation
- 12 hour schedule difference
Software quality has ultimately always been around requirements and understanding the problems being solved. That's already hard enough with collocated native speakers.
On top of this is the fundamental master/slave or imperialistic nature to first world/"third world" software development. It is of course buried under self-interest, desperation, and "professionalism". This will always lead to a reduced sense of involvement in the code and mission of the project.
There is the educational issues, where India values memorization and and devalues creativity and independent thought. Where those exist in Indian workers, the regimented nature of orgs over there (related to the imperalism vibe) stamp them out, and the rest is lost in other language and culture barriers.
I would also hazard to say that India is much more obsessed with cultural status (echoes of the caste system), and low software developer jobs aren't good enough on the hierarchy. They aren't Brahmin. Brahmins are managers and leaders.
Of course the cultural barrier represents a turf war. Indians want to own sections of code/orgs with just Indians. The managers explicitly scheme this. Of course all middle managers scheme, so I don't want to seem like I'm casting Indian managers as any more sociopathic than US ones. But it is still a turf war that divides along racial lines. The US-side companies expect multicultural cooperative work. Unless there is the owner/master dynamic, you don't see Americans of non-indian descent working in India except as liasons or owners/managers/bosses.
It's all related to the lifespan arc of software. The software is made/architected in the first world, and eventually is handed off for "maintenance" to outsourcing. Eventually that becomes untenable, and a full rewrite or rearchitecture is performed, and the cycle begins anew.
I apologize if anything I wrote offended anyone, I wanted to be as dispassionate as possible.